Gas conductive sensor technology and application
光电传感器(中英文对照版)
Photoelectric sensorKey word: photoelectric effect photoelectric element photoelectric sensor classification sensor application characteristics .Abstract: in the rapid development of science and technology in the modern society, mankind has into the rapidly changing information era, people in daily life, the production process, rely mainly on the detection of information technology by acquiring, screening and transmission, to achieve the brake control, automatic adjustment, at present our country has put detection techniques listed in one of the priority to the development of science and technology. Because of microelectronics technology, photoelectric semiconductor technology, optical fiber technology and grating technical development makes the application of the photoelectric sensor is growing. The sensor has simple structure, non-contact, high reliability, high precision, measurable parameters and quick response and more simple structure, form etc, and flexible in automatic detection technology, it has been widely applied in photoelectric effect as the theoretical basis, the device by photoelectric material composition. Text:First, theoretical foundation - photoelectric effectPhotoelectric effect generally have the photoelectric effect, optical effect, light born volts effect.The light shines in photoelectric material, according to the electronic absorption material surface energy, if absorbed energy large enough electronic electronic will overcome bound from material surface and enter the outside space, which changes photoelectron materials, this kind of phenomenon become the conductivity of the photoelectric effectAccording to Einstein's photoelectron effect, photon is moving particles, each photon energy for hv (v for light frequency, h for Planck's constant, h = 6.63 * 10-34 J/HZ), thus different frequency of photons have different energy, light, the higher the frequency, the photon energy is bigger. Assuming all the energy photons to photons, electronic energy will increase, increased energy part of the fetter, positive ions used to overcome another part of converted into electronic energy. According to the law of conservation of energy:Type, m for electronic quality, v for electronic escaping the velocity, A microelectronics the work done.From the type that will make the optoelectronic cathode surface escape the necessary conditions are h > A. Due to the different materials have different escaping, so reactive to each kind of cathode materials, incident light has a certain frequency is restricted, when the frequency of incident light under this frequency limit, no matter how the light intensity, won't produce photoelectron launch, this frequency limit A -h m 212νν=called "red limit". The corresponding wavelength for type, c for the speed of light, A reactive for escaping.When is the sun, its electronic energy, absorb the resistivity reduce conductive phenomenon called optical effects. It belongs to the photoelectric effect within. When light is, if in semiconductor electronic energy big with semiconductor of forbidden band width, the electronic energy from the valence band jump into the conduction band, form, and at the same time, the valence band electronic left the corresponding cavities. Electronics, cavitation remained in semiconductor, and participate in electric conductive outside formed under the current role.In addition to metal outer, most insulators and semiconductor have photoelectric effect, particularly remarkable, semiconductor optical effect according to the optoelectronics manufacturing incident light inherent frequency, when light resistance in light, its conductivity increases, resistance drops. The light intensity is strong, its value, if the smaller, its resistance to stop light back to the original value. Semiconductor produced by light illuminate the phenomenon is called light emf, born volts effect on the effect of photoelectric devices have made si-based ones, photoelectric diode, control thyristor and optical couplers, etc.Second, optoelectronic components and characteristicsAccording to the outside optoelectronics manufacturing optoelectronic devices have photoelectron, inflatable phototubes and photoelectric times once tube.1. Phototubes phototubes are various and typical products are vacuum phototubes and inflatable phototubes, light its appearance and structure as shown in figure 1 shows, made of cylindrical metal half cathodic K and is located in the wires cathodic axis of anode in A package of smoke into the vacuum, when incident light within glass shell in the cathode, illuminate A single photon took all of its energy transfer to the cathode materials A free electrons, so as to make the freedom electronic energy increase h. When electrons gain energy more than escape of cathode materials, it reactive A metal surface constraints can overcome escape, form electron emission. This kind of electronic called optoelectronics, optoelectronic escaping the metal surface for after initial kinetic energyPhototubes normal work, anode potential than the cathode, shown in figure 2. In one shot more than "red light frequency is premise, escape from the optoelectronic cathode surface by positive potential attracted the anode in photoelectric tube forming space, called the current stream. Then if light intensity increases, the number of photons bombarded the cathode multiplied, unit of time to launch photoelectron number are also increasing, photo-current greatens. In figure 2 shows circuit, current and resistance is the voltage drop across the only a function of light intensity relations, so as to achieve a photoelectric conversion. When the LTT optoelectronic cathode K, electronic escape from the cathode surface, and was the photoelectric anode is an electric current, power plants absorb deoxidization device in the load resistance - I, the voltagePhototubes photoelectric characteristics fig.03 shows, from the graph in flux knowable, not too big, photoelectric basic characteristics is a straight line.2. Photoelectric times had the sensitivity of vacuum tube due to low, so with people developed has magnified the photomultiplier tubes photo-current ability. Figure 4 is photomultiplier tube structure schematic drawing.图4光电倍增结构示意图From the graph can see photomultiplier tubes also have A cathode K and an anode A, and phototubes different is in its between anode and cathode set up several secondary emission electrodes, D1, D2 and D3... They called the first multiply electrode, the second multiply electrode,... Usually, double electrode for 10 ~ 15 levels. Photomultiplier tubes work between adjacent electrode, keeping a certain minimum, including the cathode potential potentials, each multiply electrode potential filtering increases, the anode potential supreme. When the incident light irradiation, cathodic K escape from the optoelectronic cathode multiplied by first accelerated, by high speed electrode D1 bombarded caused secondary electron emission, D1, an incident can generate multiple secondary electron photonics, D1 emit of secondary electron wasD1, D2 asked electric field acceleration, converged on D2 and again produce secondary electron emission... So gradually produce secondary electron emission, make electronic increased rapidly, these electronic finally arrived at the anode, form a larger anode current. If a n level, multiply electrodes at all levels for sigma, the multiplication of rate is the multiplication of photomultiplier tubes can be considered sigma n rate, therefore, photomultiplier tube has high sensitivity. In the output current is less than 1mA circumstances, it in a very wide photoelectric properties within the scope of the linear relationship with good. Photomultiplier tubes this characteristic, make it more for light measurement.3 and photoconductive resistance photoconductive resistance within the working principle is based on the photoelectric effect. In semiconductor photosensitive material ends of mount electrode lead, it contains transparent window sealed in the tube and shell element photoconductive resistance. Photoconductive resistance properties and parameters are:1) dark resistance photoconductive resistance at room temperature, total dark conditions stable resistance called dark resistance, at the current flow resistance is called dark current.2) light resistance photoconductive resistance at room temperature and certain lighting conditions stable resistance measured, right now is called light resistance of current flow resistance is called light current.4, volt-ampere characteristics of both ends photoconductive resistance added voltage and current flows through photoconductive resistance of the relationship between called volt-ampere characteristics shown, as shown in figure 5. From the graph, the approximate linear volt-ampere characteristics that use should be limited, but when the voltage ends photoconductive resistance, lest than shown dotted lines of power consumption area5, photoelectric characteristics photoconductive resistance between the poles, light when voltage fixed the relationship between with bright current photoelectric characteristics. Called Photoconductive resistance photoelectric characteristics is nonlinear, this is one of the major drawback of photoconductive resistance.6, spectral characteristics is not the same incident wavelength, the sensitivity of photoconductive resistance is different also. Incidence wavelength and photodetector the relationship between relative sensitivity called spectral characteristics. When used according to the wavelength range by metering, choose different material photoconductive resistance.7, response time by photoconductive resistance after photo-current need light, over a period of time (time) rise to reach its steady value. Similarly, in stop lightphoto-current also need, over a period of time (down time) to restore the its dark current, this is photoconductive resistance delay characteristics. Photoconductive resistance rise response time and falling response time about 10-1 ~ 10-3s, namely the frequency response is 10Hz ~ 1000Hz, visible photoconductive resistance cannot be used in demand quick response occasion, this is one of the main photoconductive resistance shortcomings.8 and temperature characteristic photoconductive resistance by temperature affects greatly, temperature rise, dark current increase, reduced sensitivity, which is another photoconductive resistance shortcomings.9, frequency characteristic frequency characteristics refers to an external voltage and incident light, strong must be photo-current I and incident light modulation frequency, the relationship between the f, photoelectric diode is the frequency characteristic of the photoelectric triode frequency characteristics, this is because of the photoelectrictriode shot "yankees there capacitance and carrier base-combed need time's sake. By using the principle of the photoelectric efficiency of optoelectronics manufacturing frequency characteristics of the worst, this is due to capture charge carriers and release charge need a certain time's sake.Three, photoelectric sensorsPhotoelectric sensor is through the light intensity changes into electrical signal changes to achieve control, its basic structure, it first figure 6 by measuring the change of change of converting the light signal, and then using photoelectric element further will light signals into electrical signal by photoelectric sensor general. Illuminant, optical path and optoelectronics. Three components of photoelectric detection method has high precision, fast response, non-contact wait for an advantage, but measurable parameters of simple structure, sensors, form flexible, therefore, photoelectric sensor in the test and control is widely used.By photoelectric sensor generally is composed of three parts, they are divided into: transmitter and receiver and detection circuit shown, as shown in figure 7, transmitter aimed at the target launch beam, the launch of the beam from semiconductor illuminant, general light emitting diode (LED), laser diode and infrared emission diode. Beam uninterrupted launch, or change the pulse width. Receivers have photoelectric diode, photoelectric triode, composed si-based ones. In front of the receiver, equipped with optical components such as lens and aperture, etc. In its back is detection circuit, it can filter out effective signal and the application of the signal. In addition, the structural components in photoelectric switch and launch plate and optical fiber, triangle reflex plate is solid structure launch device. It consists of small triangle cone of reflective materials, can make a beam accurately reflected back from plate, with practical significance. It can be in with the scope of optical axis 0 to 25, make beams change launch Angle from a root almost after launch line, passes reflection or from the rotating polygon.some basic returns.图7Photoelectric sensor is a kind of depend on is analyte and optoelectronics and light source, to achieve the relationship between the measured purpose, so the light source photoelectric sensor plays a very important role, photoelectric sensor power if a constant source, power is very important for design, the stability of the stability of power directly affect the accuracy of measurement, commonly used illuminant have the following kinds:1, leds is a change electric energy into light energy semiconductor devices. It has small volume, low power consumption, long life, fast response, the advantages of high mechanical strength, and can match and integrated circuits. Therefore, widely used in computer, instruments and automatic control equipment.2, silk light bulb that is one of the most commonly used illuminant, it has rich infrared light. If chosen optoelectronics, constitutes of infrared sensor sensitive colour filter can be added to the visible tungsten lamps, but only filter with its infrared does illuminant, such, which can effectively prevent other light interference.3, compared with ordinary light laser laser with energy concentration, directional good, frequency pure, coherence as well as good, is very ideal light sources.The light source, optical path and photoelectric device composition photoelectric sensor used in photoelectric detection, still must be equipped with appropriate measurement circuit. The photoelectric effect to the measurement circuit of photoelectric element of widerange caused changes needed to convert the voltage or current. Different photoelectric element, the measurement circuit required is not identical also. Several semiconductor introduces below optoelectronic devices commonly used measurement circuit.Semiconductor photoconductive resistance can through large current, be in so usually, need not equipped with amplifier. In the output power of demand is bigger, can use figure 8 shows circuit.Figure 9 (a) with temperature compensation given the photosensitive diode bridge type measuring circuit. When the incident light intensity slow change, the reverse resistance photosensitive diode is the slow change, the change of the temperature will cause the bridge output voltage, must compensate. Drift Picture a photosensitive diode as the test components, another into Windows, in neighboring bridge, the change of the temperature in the arms of the influence of two photosensitive diode, therefore, can eliminate the same output with temperature bridge road drift.Light activated triode incident light in work under low illumination, or hope to getbigger output power, also can match with amplifying circuit, as shown in figure 9 shows.Because even in the glare photosensitive batteries, maximum output voltage also only 0.6 V, still cannot make the next level 1 transistor have larger current output, so must add positive bias, as shown in figure 9 (a) below. In order to reduce the transistor circuit impedance variations, base si-based ones to reduce as much as possible without light, when the reverse bias inherit in parallel a resistor si-based ones at both ends. Or like figure 9 (b) as shown by the positive ge diode produces pressure drop and test the voltage produced when exposed to light, make silicon tube e stack, b the voltage between actuators than 0.7 V, and conduction work. This kind of circumstance also can use silicon light batteries, as shown in figure 10 (c) below. Semiconductor photoelectric element of photoelectric circuit can also use integrated operational amplifier. Silicon photosensitive diode can be obtained by integratingop-amp larger output amplitude, as shown in figure 11 (a) below. When light is produced, the optical output voltage in order to guarantee photosensitive diode isreverse biased, in its positive to add a load voltage. Figure 11. (b) give the photocell transform circuit, because the photoelectric si-based ones short-circuit current and illumination of a linear relationship between, so will it up in the op-amp is,inverse-phase input, using these two potential difference between the characteristicsof close to zero, can get better effect. In the picture shows conditions, the output voltageThe photoelectric element by flux the role of different made from the principle of optical measurement and control system is varied, press the photoelectric element (optical measurement and control system) output nature, namely, can be divided into second analog photoelectric sensor and pulse (switch) photoelectric sensor. Analog photoelectric sensors will be converted into continuous variation of the measure, it is measured optical with a single value relations between analog photoelectric sensor. According to be measured (objects) method detection of target can be divided into transmission (absorption) type, diffuse type, shading type (beam resistance gears) three categories. So-called transmission style means the object to be tested in optical path in constant light source, the light energy through things, part of being measured by absorption, transmitted light onto photoelectric element, such as measured liquid, gas transparency and photoelectric BiSeJi etc; speed.gratifying The so-called diffuse style means the constant light by the light onto the analyte from the object to be tested, and projected onto surfaces reflect on after optoelectronic devices, such as photoelectric colorimetric thermometer and light gauge etc; The so-called shading style means the when illuminant issued by the flux of light analyte covered by a part Jing optoelectronics, make projection on the flux change, change the object to be tested and extent of the position with the light path, such as vibration measurement, the size measurement; And in pulse photoelectric sensor in the sensors, photoelectric element acceptable optical signal is intermittent change, therefore photoelectric element in switch work of the state, the current output it is usually only two steady state of the signal, the pulse form used for photoelectric counting and photoelectric speed measurement and so on.And infrared photoelectric sensor classification and working way generally have thefollowing kinds:1, groove photoelectric sensor put a light emitter and a receiver in a slot face-to-face outfit are on opposite sides of the photoelectric groove. Lighter emits infrared light or visible light, and in unimpeded cases light receptors can receive light. But when tested objects from slot zhongtong obsolete, light occluded, photoelectric switches and action. Output a switch control signal, cut off or connect load current, thus completing a control movement. Groove switch is the overall of detection distance because general structure limits only a few centimeters.2, DuiShe type optoelectronic sensor if you put lighter and receive light is separated, can make the detection distance increase. By a lighter and an inbox light sensor into a photoelectric switch is called DuiShe separate photoelectric switches, referred to DuiShe photoelectric switch. Its detection distance can reach a few meters and even a dozen meters. When using light-emitting device and receive light device are installed in test object through the path of the sides, test object by blocking light path, accept light implement action output a switch control signals.3, reflex plate.it photoelectric switch light-emitting device type and receive light device into the same device inside, in its front pack a reflex plate.the using the reflection principle of complete photoelectric control function is called reflex plate.it reflex (or reflector reflex) photoelectric switch. Under normal circumstances, lighter the light reflected by reflex plate.it is received by accept light; Once the light path be test object to block, accept light, the light is not receive photoelectric switch is action, output a switch control signals.4, diffusion reflective photoelectric switches its detection head with a lighter and also an inbox light ware, but no reflex plate.it ahead. Normally lighter for the light collect light is not found. When test object by blocking the light, and the light reflected light, receive part implement received light signals, output a switch signals.Four, I'm the idea of photoelectric sensorWith the development of science and technology people on measuring accuracy had the higher request, this has prompted the pace with The Times photoelectric sensor have updated, improve the main means photoelectric sensor performance is the application of new materials, new technology manufacturing performance is more superior photoelectric element. For example, today the prototype of the photoelectric sensor is a small metal cylindrical equipment, with a calibration lens, transmitter into receiver focused light, the receiver out of cable to the device got a vacuum tube amplifiers in metal cylinder on the incandescent light bulb inside a small as the light source a strong incandescent lamp sensor. Due to the sensor various defects existing in the fields, gradually faded. To appear, because of it of fiber of excellent performance, then appeared with sensors supporting the use of optical passive components, another fiber without any interference of electromagnetic signal, and can make the sensor of the electronic components and other electrical disturbance in isolation. Have a piece of plastic optical fiber core or glass light core, light outside a metallic core skins and bread this layer metal cortical density lower than light core, so low, the beam refraction in the two materials according to the border (incident Anglewithin a certain range, reflected), is all. Based on optical principle, all beams can be made by optical fiber to transmission. Two incident beam Angle in an Angle (along the fiber length direction within) by multiple reflections from the other end after injection, another incident angles than accept the incident light in metal skin, loss. This accept Angle within the biggest incident Angle than two times, this is because fiber slightly larger from air into density larger fiber materials hitting may have a slight refraction. In light of the optical fiber transmission from inside the influence of fiber bending (whether more than bending radius minimal bending radius). Most optical fiber is flexible, easy to install in the narrow space. Photoelectric sensor is a kind of non-contact measurement small electronic measurement equipment, rely on detect its receives the light intensity change, to achieve measurement purposes, andit's also a vulnerable to external disturbance and lose the measurement accuracy of the device. When be being designed so besides the choice optoelectronic components, still must set GSCC signal and temperature compensating measures used to weaken or eliminate the impact of these factors.Photoelectric sensor must pass a light modulation, like radio waves of light modulation of sends and receives, the radio to a station, can ignore other radio signal sensors without modulation long-focal-length only through the use of mechanical shielded, scenes that receiver transmitter only can receive the emission of light, can make its energy becomes very high. In contrast, through modulation transceivers can ignore ambient light, only to own light or with the same modulation frequencies of light without modulation response. The sensor used to test the infrared rays or around the radiation, if just baked red bottle, in this application situation if use other sensor, may be incorrect actions.Photoelectric sensor due to non-contact, high reliability, etc, and to change in measurement, damage the object to be testedSo since its invention in fields since play a significant role, at present it has been widely used in measuring mechanical quantity, thermal quantity, weight, intelligent vehicle system into etc. Now it in power system automatically grid device plays a very important role, because generator input power grid operation often USES accurate with law, must meet: three-phase line sequence is consistent, frequency, phase agree unanimously, voltage amplitude equal, one of the conditions in system design has been satisfied, after three conditions must also meet to grid, of course, artificially grid is more difficult, photoelectric grid is easier.The development of times, science and technology in the update, photoelectric sensor types are increasing and application domain more and more widely, such as a recent kind of infrared already in intelligent vehicle electrical sensors in to the application, one of which had based on infrared sensor is the core of intelligent vehicle, reflective type infrared sensor using reflex infrared sensor design path detection module and speed monitoring module; Another method based on infrared sensor using the car tracing is to collect infrared sensor data.Photoelectric sensor has cannot be replaced by other sensors superiority, so it development foreground is very good, the application will also become more widespread.光电传感器关键字：光电效应 光电元件 光电特性 传感器分类 传感器应用 摘要：在科学技术高速发展的现代社会中，人类已经入瞬息万变的信息时代，人们在日常生活，生产过程中，主要依靠检测技术对信息经获取、筛选和传输，来实现制动控制，自动调节，目前我国已将检测技术列入优先发展的科学技术之一。
传感器的工作原理
传感器的工作原理Working Principles of Sensors。
Sensors are electronic devices that are designed to detect and respond to changes in the environment. They are widely used in various industries and applications, such as automotive, aerospace, medical, and consumer electronics. The working principles of sensors vary depending on their types and functions. In this article, we will discuss the most common working principles of sensors.1. Resistive Sensors。
Resistive sensors are based on the principle of changing resistance in response to changes in the environment. They consist of a sensing element and a signal conditioning circuit. The sensing element is made of a material that changes its resistance when exposed to a specific stimulus, such as temperature, pressure, or humidity. The signal conditioning circuit amplifies andconverts the resistance change into a measurable output signal, such as voltage or current.The most common types of resistive sensors are thermistors, strain gauges, and humidity sensors. Thermistors are used to measure temperature, strain gauges are used to measure strain and force, and humidity sensors are used to measure humidity.2. Capacitive Sensors。
GAS SENSOR
专利名称：GAS SENSOR发明人：FUJIOKA TORU,KAWAMURA HIDEO,KAWAI TOMOJI申请号：JP18636185申请日：19850823公开号：JPS6246247A公开日：19870228专利内容由知识产权出版社提供摘要：PURPOSE:To provide the titled gas sensor suitable for the selective detection of gas to be inspected, requiring no maintenance and easy to handle, by setting the electrical change of a semiconductive photocatalyst material generating by gas to be inspected at the time of the irradiation of light to a gas detecting signal. CONSTITUTION:A gas sensor 1 has a three-layered structure wherein a Pt-layer 3 is mounted to the upper surface of a TiO2-layer and a Ti-layer 4 is mounted to the under surface of said TiO3 layer 2. As lead wires, Au-wires 5, 5' are respectively adhered to the layers 3, 4 one at a time by conductive pastes 6, 6'. Further, the layers 2, 4 are connected so as to obtain ohmic contact. When a shot key barrier is formed, the separation of carriers generated in the layer 2, that is, an electron and a positive hole is rapidly performed and, therefore, the reaction of gas to be inspected and the carriers is promoted while it can be prevented that the electron and the positive hole generated at once are rebonded in the layer 2 and distincted. Therefore, efficient redox reaction is performed between the molecule of the gas to be inspected transmitted through the porous Pt-layer to be contacted with the layer 2 and the positive hole successively appearing to the surface.申请人：MATSUSHITA ELECTRIC WORKS LTD 更多信息请下载全文后查看。
Gas Sensing Materials and Devices
Gas Sensing Materials and DevicesGas sensing materials and devices play a crucial role in various fields such as environmental monitoring, chemical analysis, safety and security, medical diagnosis, and industrial applications. They are designed to detect and measure the concentration of gases such as carbon dioxide, carbon monoxide, methane, ammonia, and many others. The development of gas sensing materials and devices has greatly contributed to the advancement of these fields and has led to a better understanding of gas interactions and their effects on the environment and human health.Overview of Gas Sensing MaterialsGas sensing materials can be classified into two categories: organic and inorganic materials. Organic materials include polymers, carbon-based materials, and organic molecules. Inorganic materials, on the other hand, include metal oxides, conducting polymers, and semiconductors.Metal oxide gas sensors are the most widely used type of gas sensor due to their high sensitivity, low cost, and ease of fabrication. They are composed of a metal oxide thin film deposited onto a substrate and are capable of detecting a wide range of gases. The metal oxide thin film interacts with the target gas, causing a change in resistance, which is then measured and used to calculate the gas concentration.Semiconductor gas sensors are another type of inorganic gas sensor commonly used in the industry. They are based on the principle of changes in electrical conductivity when exposed to the target gas. The semiconductor material interacts with the gas through the adsorption and desorption of gas molecules, which causes changes in the concentration of free charge carriers. These changes in charge carriers are then measured and used to calculate the gas concentration.Polymer gas sensors are a type of organic gas sensor that operates based on the principle of swelling of the polymer film when exposed to gas. The swelling of the polymer leads to changes in its optical, mechanical, or electrical properties, which can bemeasured and used to determine the gas concentration. Polymer gas sensors are more sensitive to gas concentrations than metal oxide or semiconductor sensors, but they are also more expensive to produce.Gas Sensing DevicesGas sensing devices are designed to incorporate gas sensors into a device that is capable of measuring gas concentrations in real-time. The devices can be classified into three categories: handheld, portable, and fixed devices.Handheld devices are compact and easy to use, making them ideal for use in small spaces. They are commonly used in air quality monitoring, combustible gas detection, and personal safety applications.Portable devices are larger and more durable than handheld devices, but they are still relatively lightweight and easy to use. They are commonly used in industrial settings where gas detection is necessary for safety and compliance purposes.Fixed devices are the largest and most complex type of gas sensing device. They are permanently installed in buildings and other facilities and are used to detect gas leaks and ensure the safety of the occupants. Fixed devices can be connected to building automation systems to provide real-time gas monitoring and control.Applications of Gas sensing materials and devices have a wide range of applications in various fields. Some of the most common applications include:Environmental monitoring: Gas sensing devices are used to monitor air quality and identify pollutants in the environment. They are commonly used in urban areas to measure levels of carbon dioxide, carbon monoxide, and nitrogen oxides.Industrial applications: Gas sensing devices are used in industrial settings to detect gas leaks and ensure the safety of workers. They are commonly used in the petrochemical, manufacturing, and mining industries.Medical diagnosis: Gas sensing devices are used in medical diagnosis to detect gases that are produced by the body during certain diseases. For example, acetone is producedby the body when a person has diabetes, and gas sensors can be used to measure the concentration of acetone in a patient's breath.ConclusionIn conclusion, gas sensing materials and devices are essential tools for the detection and measurement of gases in various fields. The development of gas sensing materials and devices has greatly contributed to the advancement of these fields and has led to a better understanding of gas interactions and their effects on the environment and human health. With continued research and development, gas sensing materials and devices will continue to improve, allowing for greater precision and accuracy in gas detection and measurement.。
Gas sensor
专利名称：Gas sensor发明人：Joel Abdullah,Alexei Tikhonski,Ronald I.Dass,James Novak申请号：US12543260申请日：20090818公开号：US08117894B2公开日：20120221专利内容由知识产权出版社提供专利附图：摘要：A sensor system issues measurement commands at a predetermined regular rate. If a measurement indicates that a gas of interest is present, then the sensor system is signaled to wake-up thereby pulsing a heater for the sensor element that improves theaccuracy of measurements. Measurements of humidity, temperature and gas concentration are made. If the gas of interest is detected then the data is used to indicate a compensated gas measurement. The gas level is classified as to its hazard and an adaptive detection algorithm is used to set an activity mode. If the gas of interest is not detected, the adaptive detection algorithm is used to set a sleep mode that saves power. Measurement rates are kept constant while heater power is controlled to reduce power consumption. Measurement rates are changed to increase concentration sensitivity.申请人：Joel Abdullah,Alexei Tikhonski,Ronald I. Dass,James Novak地址：Austin TX US,Cedar Park TX US,Austin TX US,Austin TX US国籍：US,US,US,US代理机构：Matheson Keys Garsson & Kordzik PLLC代理人：Kelly Kordzik更多信息请下载全文后查看。
生物反馈治疗仪说明书
MYOTRAC INFINITIDual SEMGThe Manufacturer: Thought Technology Ltd.2180 Belgrave AvenueMontreal, Quebec, CanadaH4A 2L8Product Name: MyoTrac Infiniti System Product #: T9800Device Name: MyoTrac Infiniti Encoder Device #: SA9800•Type BF Equipment •Internally powered equipment•Continuous operation•Read Instruction Manual•The pins of the connectors identified with the ESD warning symbol should not be touched unless ESB precautionary procedures are used.CAUTION•US Federal Law restricts this device to sale by, or on order of, a physician or any otherpractitioner licensed by the law of the state in which he or she practices to use or order theuse of this device.WARNING•Do not operate Active Sensors within 10 feet of an operating cellular phone, similar radio transmitting device, other powerful radio interference producing sources such as arcwelders, radio thermal treatment equipment, x-ray machines, or any other equipment thatproduces electrical sparks. Portable and mobile RF communication equipment can affectthis equipment.•With the MyoTrac Infiniti Encoder SA9800 use only with supplied power supply. GlobTek Part Number WR92B2500LF9P-Y-MED (WR95/WR93/WR97) or GS889•The PC used with MyoTrac Infiniti must be placed outside the patient/client environment(more than 3 meters or 10 feet) or the PC must comply with EN60601-1 (system safety).•After use, the Batteries or the Battery pack must be disposed of in accordance with local, state and federal regulations and laws.•After use, the Disposable Electrodes may be a biohazard. Handle, and when applicable, dispose of these materials in accordance with accepted medical practice and any applicablelocal, state and federal laws and regulations.•Reusable electrodes present a potential risk of cross-infection especially when used onabraded skin, unless they are restricted to a single patient or sterilized between patients. Ifsterilizing electrodes, employ only gas sterilization.•Radiated radio frequency electromagnetic fields can cause performance degradation in the MyoScan-Pro EMG sensor. In the worst case, an RF field strength of 22mV/M can causean increase of 1μV in the signal reading from a MyoScan-Pro sensor. Be sure to keep inmind that a very relaxed muscle should provide an EMG reading of approximately 1-3μV.•This device is capable of generating current densities exceeding 2mA r.m.s./cm² this may require special attention of the operator.•Avoid accidental contact between connected but unused applied parts and other conductive parts including those connected to protective earth.•Explosion Hazard; Do not use in the presence of a flammable anesthetic mixture with air, or with Oxygen or Nitrous Oxide.•Not to be immersed in water.•Take care in arranging patient and sensor cables to avoid risk of patient entanglement or strangulation.•The operator is responsible for ensuring the safety of any devices controlled or triggered by Infiniti equipment or software, or by any software or hardware receiving data from Infinitiequipment. Infiniti equipment must not be configured or connected in such a way thatfailure in its data acquisition, processing or control functions can trigger patient feedbackstimulus that poses an unacceptable level of risk.•Use of any equipment in a biofeedback or stimulation context should be immediatelyterminated upon any sign of treatment-related distress or discomfort.•Not to be connected to a patient undergoing MRI, Electro surgery or defibrillation.•Not for use with patients with undiagnosed pain conditions.•Only use the unit for which it was prescribed.•Do not immerse the unit in water or any other liquid substance.•Do not use if you have symptoms of bladder infection.•Do not use with diminished mental capacity or physical competence limiting the use of the device.•Caution should be used for patients with suspected or diagnosed heart problems.•Caution should be used for patients with suspected or diagnosed epilepsy.•Electrode placement and stimulation settings should be based on the guidance of theprescribing practitioner.•If damage is evident of the unit or accessories, discontinue use and contact your supplierfor further information on repair.•The system should not be used adjacent to or stacked with other equipment, if usedadjacent or stacked the unit should be observed to verify normal operation in theconfiguration in which it will be used.•Use of accessories, transducers or cables other than those specified by ThoughtTechnology ltd may result in increased emissions or decreased immunity of the equipmentto electromagnetic energy.ATTENTION•Sensors and equipment damaged by static electricity are not covered under warranty. Toprevent static discharge from damaging the sensor and/or encoders, use anti-static mats orsprays in your working area. A humidifier may also be used to prevent static environmentsby conditioning hot, dry air. It is recommended that all staff involved with the unit receive anexplanation of the ESD symbol and the precautions described above as a minimum.•Do not apply any electrode gel or equivalent directly on the sensor snaps. Always useelectrodes as a medium between the sensor and the client.•Not for diagnostic purposes, not defibrillator proof, not for critical patient monitoring.•To prevent voiding warranty by breaking connector pins, carefully align white guiding dot onsensor plug with slot on sensor input.•Make sure to remove electrodes from sensor snaps immediately after use.•Do not plug third party sensors directly into instrument inputs. Plug only ThoughtTechnology Active Sensor cable connectors into instrument inputs. All electrodes and thirdparty sensors must be connected to active sensors, either directly or through an adapter.•Remove batteries when the device is not being used for an extended period of time. Pleasedispose of battery following local regulations.INTENDED PURPOSE•Biofeedback, Relaxation & Muscle Re-Education purposes•Relaxation of muscle spasms•Prevention or retardation of disuse atrophy•Increasing local blood circulation•Muscle re-education•Maintaining or increasing range of motionNOTE•No preventative inspections required; maintenance must be performed by qualified personnel.Factory re-calibration can be requested.•The supplier will make available, upon request, circuit diagrams, component parts lists anddescription or other information required for the repair of product by qualified personnel.•The operator must be familiar with typical characteristics of signals acquired by thisequipment, and be able to detect anomalies in the acquired signal that could interfere withtreatment effectiveness. Depending on the importance of signal integrity, it may be advisableto continuously monitor the raw signals, in time and/or frequency domain, while the device isbeing used for biofeedback or other purposes. If anomalies are observed on acquired signals,and if you suspect a problem with electromagnetic interference, contact Thought Technologyfor a technical note on identification and remediation.•This product conforms to standards EN60601-1, EN60601-2-10 and EN60601-2-40; someencoder labeling may indicate superceded standards.MAINTENANCE AND CALIBRATION•Wipe encoder with a clean cloth•Factory testing and calibration ensure equipment accuracy and frequency response. Contact Thought Technology for factory re-calibration if necessary.STORAGE•Store in its original case at up to 90% humidity / 30C°TRANSPORTATION•Transport in its original caseManual # SA9814 Rev 4Guidance and manufacturer’s declaration – electromagnetic immunity The MyoTrac Infiniti is intended for use in the electromagnetic environment specified below. The customer or the user of the MyoTrac Infiniti should assure that it is used in such an environment, and that precautions regarding that environment are heeded.Immunity test IEC 60601test level Compliance level Electromagnetic environment –guidanceElectrostatic discharge (ESD) IEC 61000-4-2 ±6 kV contact±8 kV air±6 kV contact±8 kV airFloors should be wood, concrete orceramic tile. If floors are covered withsynthetic material, the relative humidityshould be at least 30 %.Electrical fast transient/burst IEC 61000-4-4 ±2 kV for powersupply lines±1 kV for input/outputlines±2 kV for powersupply lines±1 kV for input/outputlinesMains power quality should be that of atypical commercial or hospitalenvironment.SurgeIEC 61000-4-5 ±1 kV differentialmode±2 kV common mode±1 kV differentialmode±2 kV common modeMains power quality should be that of atypical commercial or hospitalenvironment.Voltage dips, short interruptions and voltage variations on power supply input linesIEC 61000-4-11 <5 % U T(>95 % dip in U T)for 0,5 cycle40 % U T(60 % dip in U T)for 5 cycles70 % U T(30 % dip in U T)for 25 cycles<5 % U T(>95 % dip in U T)for 5 sec<5 % U T(>95 % dip in U T)for 0,5 cycle40 % U T(60 % dip in U T)for 5 cycles70 % U T(30 % dip in U T)for 25 cycles<5 % U T(>95 % dip in U T)for 5 secMains power quality should be that of atypical commercial or hospitalenvironment. If the user of theMyoTrac Infiniti requirescontinued operation during powermains interruptions, it is recommendedthat the MyoTrac Infiniti bepowered from an uninterruptible powersupply or a battery.Power frequency (50/60 Hz) magnetic field IEC 61000-4-8 3 A/m 3 A/m Power frequency magnetic fieldsshould be at levels characteristic of atypical location in a typical commercialor hospital environment.NOTE U T is the a.c. mains voltage prior to application of the test level.NOTE 1 At 80 MHz and 800 MHz, the higher frequency range applies.NOTE 2 These guidelines may not apply in all situations. Electromagnetic propagation is affected by absorption Field strengths from fixed transmitters, such as base stations for radio (cellular/cordless) telephones and land mobile radios, amateur radio, AM and FM radio broadcast and TV broadcast cannot be predicted theoretically with accuracy. To assess the electromagnetic environment due to fixed RF transmitters, an electromagnetic site survey should be considered. If the measured field strength in the location in which the MyoTrac Infiniti is used exceeds the applicable RF compliance level above, the MyoTrac Infiniti should be observed to verify normal operation. If abnormal performance is observed, additional measures may be necessary, such as reorienting or relocating the MyoTrac Infiniti.Over the frequency range 150 kHz to 80 MHz, field strengths should be less than [V1] V/m.Guidance and manufacturer’s declaration – electromagnetic emissionsThe MyoTrac Infiniti is intended for use in the electromagnetic environment specified below. The customer or the user of the MyoTrac Infiniti should assure that it is used in such an environment.Emissions test Compliance Electromagnetic environment – guidanceRF emissions CISPR 11 Group 1 The MyoTrac Infiniti uses RF energy only for its internal function.Therefore, its RF emissions are very low and are not likely tocause any interference in nearby electronic equipment.RF emissionsCISPR 11Class BHarmonic emissionsIEC 61000-3-2Not applicableVoltage fluctuations/ flicker emissions IEC 61000-3-3 Not applicableThe MyoTrac Infiniti is suitable for use in all establishments,including domestic establishments and those directly connected tothe public low-voltage power supply network that suppliesbuildings used for domestic purposes.Table of ContentsAbout This Guide (9)Chapter 1 (10)Introduction to your MYOTRAC INFINITI™ Dual SEMG Encoder (10)System Requirements (11)MyoTrac Infiniti Components (12)Connection to the Client (15)Connection to the PC (19)Screen Elements (20)Thought Support (20)Settings Menu (21)Chapter 2 (25)SEMG sessions on your MYOTRAC INFINITI™ Dual SEMG Encoder (25)Open SEMG Sessions (25)Script SEMG Sessions (27)Chapter 3 (28)Data Management on your MYOTRAC INFINITI™ Dual SEMG Encoder (28)MyoTrac Infiniti Review (29)Chapter 4 (30)Display Options on your MYOTRAC INFINITI™ Dual SEMG Encoder (30)Displays (30)Chapter 5 (34)Flow on your MYOTRAC INFINITI™ Dual SEMG Encoder (34)Chapter 6 (35)Reference (35)Technical Support and Order Placing (36)Technical Support (36)Product Numbers & Accessories (37)Placing Orders (38)Specifications (39)MyoTrac Infiniti Hardware Copyright Notice (44)About This Guide Welcome to the MYOTRAC INFINITI™ encoder. This guide is designed to help you get up and running quickly with your new encoder. It will describe the operation of the encoder, and how it interfaces to the host personal computer (PC).It walks you through:•Physical Operation of the encoder.• EMG sessions.• Data management.• Display options.After you have become familiar with the key concepts of your new encoder, you can use the rest of this guide as a reference for less common tasks, and also as a source of information if you have problems operating it.Chapter 1 Introduction to your MYOTRAC INFINITI™ Dual SEMG EncoderThis chapter explains the physical interface with the MyoTrac Infiniti Encoder, how to use it for the first time, and how to transfer data to the host PC.Getting to know your MyoTrac Infiniti Dual SEMG EncoderWhat is a MyoTrac Infiniti Dual SEMG Encoder?The MyoTrac Infiniti is the cutting edge in handheld, dual channel Surface Electromyography(SEMG). With it you will be able to deliver targeted and customized treatment directly to the client’s clinically relevant areas.A simple first approach has been adopted in the design of the MyoTrac Infiniti to make it as easyand fast as possible to get the clinical results desired from this powerful device.Customizing the MyoTrac Infiniti to your clinical needs couldn’t be easier; all users input is directed through a series of intuitive and guided screens using touch screen technology.The partnership of the MyoTrac Infiniti with the BioGraph Infiniti PC software enhances yet further the power and flexibility of the MyoTrac Infiniti. This link enables you to transfer session data to the PC for further viewing, analysis and reporting, in real time or post session.System RequirementsTo install the BioGraph Infiniti software, your computer system must meet or exceed the following requirements.•IBM PC compatible(Intel/Pentium/Celeron family or AMDK6/Athlon/Duron family, CPU P4 speed 3GHz or higher), Desktop or Laptop withtwo monitor capability•Windows 2000/XP Professional or Home edition.•50 - 60 gigabytes hard disk space for video recording and processing. (Thesoftware needs 2.5 gigabytes to installand run on available hard drive space) •Memory, 512 MB of RAM or more•CD ROM or DVD drive•SVGA graphic card (1024 x 768) or higher resolution adapter & monitor•32 bit Sound Blaster compatible sound card & speakers• 1 to 4 USB ports, depending on thedesired number of MyoTrac Infinitiencoders•Mouse or compatible pointing device •MS Word 97 or higher (for printingpurposes)•Compact Flash Reader (For use with compact flash card only)•Webcam 30 frames per second (for video purposes only)NOTE: When using certain more complex screens, you must adhere to the Recommended Computer Requirements.••IBM PC compatible(Intel/Pentium/Celeron family or AMDK6/Athlon/Duron family, CPU P3speed 1.8 GHz), Desktop or Laptop •Windows 2000/XP Professional or Home edition.•10 - 20 gigabytes hard disk space •(The software needs 2.5 gigabytes to install and run on available hard drivespace)•Memory, 256 MB of RAM or more •CD ROM or DVD drive•SVGA graphic card (1024 x 768) or higher resolution adapter & monitor •16 Bit Sound Blaster compatible sound card & speakers• 1 to 4 USB ports, depending on the desired number of MyoTrac Infinitiencoders•Mouse or compatible pointing device •Word 97 or higher (for printingpurposes)NOTE: For most recent computer requirements contact Thought Technology Ltd for MAR473Update informationPeriodically updates may become available for the BioGraph Infiniti software and for the MyoTrac Infiniti Hardware. Please contact your local distributor or visit our website for further information on how to obtain updates.MyoTrac Infiniti Components•Compact Flash for increased memory capacity and one method for transfer of data to the PC.•USB for real time transfer of data to the PC.•Touch screen enables graphically guided navigation through the software.•Rugged Ergonomic Case, easy to hold or attach to the subject and will withstand the rigors of daily use.•Battery Charging jack for wall connection enables fast built-in battery charging.•Headphone Jack for stereo sound feedback (or use the built-in speaker).•Push button On/Off switch to prevent accidental switching.• 2 Channels of Surface EMG.PowerThere are three basic methods to power the MyoTrac Infiniti unit: Inserting batteries into the battery compartment of the unit, plugging it into the wall using the supplied AC adapter, or plugging it into a powered up computer using a USB cable.The MyoTrac Infiniti is available with battery charging capabilities. It will work with four standard Alkaline AAA batteries available in all consumer electrical stores. It is also possible to run the unit on removable, externally rechargeable batteries. A rechargeable battery pack is supplied with the MyoTrac Infiniti and can be charged while still inside the unit.Note: When changing batteries it is recommended to plug the unit into external power, either USB or wall transformer so that data is not lost. Failure to supply external power will result in data and script loss.The battery compartment cover slides open by pushing up using the notch provided. Place four AAA batteries in the slots, observing the polarity as illustrated. Please note that a diagram of the correct battery polarity is embossed on the inside surface of the compartment.Alternatively it is possible to use a rechargeable battery pack (Thought Technology Part Number MI1028). This battery pack is plugged into the connector in the battery compartment marked BATT. The pack then fits into the normal battery area. Note: only use battery packs from Thought Technology or authorized representative, as use of other battery packs will damage the device.A wall mounted AC power adapter, supplied with the MyoTrac Infiniti, is used to connect the unit toan electrical outlet. This can be used in conjunction with the batteries or without.The unit can also be powered from the computer via the USB cable. The cable is connected to the unit on one side and on the other side to the USB port of the computer. This can be used inconjunction with the batteries or without.Charging the BatteriesNote: exact power supply subject to change without notice.Internal ChargerIf your MyoTrac Infiniti was supplied with a wall mounted AC adapter it is possible to charge the battery pack while it is inserted in the device.Note: Only use Thought Technology Ltd supplied wall mounted chargers with this device. Failure to do so could result in potential injury. Use only GlobTek Part Number WR9אB2500LCP-Y-MED where א= 2 for North America, א=3 for Europe, א=5 for United Kingdom and א=7 for Australia with the exception of Japan where the part number is GS 889.To start the charging plug in either the wall mounted AC adaptor or the USB cable. A full charging cycle from fully empty to fully charged will take approximately 2hrs for AC adaptor and 5.5hrs for the USB cable. The unit can be used while plugged in to either power source. The charging cycle does not need to be completed in full; it can be stopped at anytime by removing the connector.When the unit is turned off while plugged into an external power source, the screen displays a battery symbol. Charging action is shown with an animation of the battery filling up. When the battery is fully charged, the symbol shows a full battery.If the unit is plugged into an external power source while it is turned off, it will start charging within one minute.The state of the battery charging is available by going to the power menu in the settings menu of the device. It indicates the current mode of power and whether the unit is currently charging the batteries.Note: The rechargeable batteries must be fully charged prior to initial use. In order for the batteries to reach full capacity it may be necessary to charge them several times (~2-8) after initial use.MemoryRecorded data can be saved using three methods - choose the one which most closely matches your usage needs. To select saving method, select the Settings menu from the main menu, and tap on the Save icon.•Internal Memory – Limited size, only the statistical summaries are recorded. Specifically, the statistics for 13 open sessions or 9 training sessions (work/rest) or 6 assessment sessions(work/rest + fast-flick + endurance) can be recorded. Data can be lost if the batteries areremoved from the unit for longer than a few minutes.•Compact Flash Card – Most flexible method of data saving: save all the raw data for review on the encoder or for download to the PC. Available in most electronics stores in a range ofmemory sizes. Since all EMG data is recorded, the amount of data that is saved to thecompact flash card depends on the size of the card:hours64MB 1.75128MB 3.5 hours256MB 7 hours512MB 14 hourshours1GB 27.5hours2GB 55.5The encoder is delivered with a protective insert in the compact flash slot. To remove it, push the button next to the slot once to eject the card. The CF card can then be inserted; you willnotice that the CF card can only be inserted one way into the encoder to protect from incorrect insertion. When inserted properly it will be flush with the encoder rear. Follow the procedure above to remove this card when no longer required, and re-insert the protective insert. CFcards require a CF card reader to transfer data to the PC. The CF cards and reader can bepurchased from most computer stores. Before its first use in the encoder, a CF card requires PC formatting using the file manager, then format the card using the BioGraph Infiniti MainApplication. Formatting and transferring CF data to the PC is covered in depth in theBioGraph Infiniti software manual.•Real Time PC Transfer – Connect to the PC via the USB and save and display the data on the PC in real time. See the following section “Connection to the PC”.Attention: Do not remove the CF card without first stopping recording. If the CF card is removed during recording, you will lose all the data for the current session.TappingLike using a mouse on a computer screen the MyoTrac Infiniti allows you to use your finger or a stylus to tap the buttons directly on the screen. The first time you start your handheld unit, or if the power has been disconnected for a while, you will be guided through a set of welcome screens including calibration, time and date setting. The calibration aligns the internal circuitry of theencoder with its touch sensitive screen so that when you tap a button on the screen, the handheld unit can detect exactly which button is being pressed. It is recommended to use a stylus when calibrating the device as it will provide a more accurate calibration than using a finger.Note:Always use a finger or stylus for tapping the screen. Never use a pen, pencil or othermarking or sharp object on the screen.Damage resulting from misuse of the screen is notcovered by the warranty.The software is designed so that once the screen has been calibrated it is possible to use all the buttons with a finger. In many cases the touch sensitive area is greater than the graphicalconstraints of the button allowing for easier operation using a finger. As necessary wipe screen with a dry cloth to clean. Screen protectors are available from good stationary suppliers and are a good way to extending the life of your screen.Connection to the ClientDepending on the type of session you are going to record there are different ways to connect the two channels to the client. Either plug the extender cable into the device directly and connect to the client with EMG electrodes, or plug them into the pre-amplifier and the pre-amplifier into the MyoTrac Infiniti.Attention: When you insert the extender cable (lead wire) into the electrode connector, MAKE SURE THAT NO BARE METAL OF THE PINS IS EXPOSED.Before applying electrodes, be sure the skin surface is cleaned and dried. Make sure theelectrodes are placed firmly to the skin and make good contact between the skin and electrodes.Please consult the clinical guide for information on electrode selection for different placements. The illustration below shows the division of the body into six areas of treatment.Arms and ShouldersHead and NeckAbdominalsBack and ButtocksLegs and HipsWhen connecting a sensor or extender cables, be sure to properly line up the guiding dot on the top of the plug with the notch in the encoder's input socket. Forcing the plug into the jack in any other position may damage your equipment.Using the MyoTrac Infiniti with AC Power Adapter or Connected to a PCThe MyoTrac Infiniti is designed for safe operation on ungrounded AC power sources. However, if you are using the MyoTrac Infiniti while it is connected to an ungrounded AC power source, for best results you may need to follow some simple guidelines for skin preparation and electrode placement. These measures will help to avoid falsely elevated EMG readings while the muscle is at rest.If you notice elevated resting EMG levels not related to the patient’s condition, and if this occurs only when the unit is connected to AC power (directly via the supplied AC adapter or indirectly via a USB connection to the PC), and if it is necessary to run the MyoTrac Infiniti on ungrounded power(i.e. no 3rd ground pin on the AC wall socket or on the PC power supply), try the followingtechniques to improve the readings.First, if you are using a PC with only 2 prongs on the wall plug and you have a grounded outlet (3 pin wall sockets with a working ground), plug the ac adapter into the MyoTrac-Infiniti and into the grounded outlet to provide a ground for the system.If you have no opportunity to ground either the PC or the AC adapter, use the following electrode placement tips:•If the EMG site is located on an extremity or limb, be sure to place the REF (black colored) electrode more proximally (on or closer to the trunk of the body) than the sense electrodes(yellow and blue), and at least ten centimeters away from either sense electrode.•Prepare the skin under all three electrodes, using a product designed for skin preparation prior to electrode application (mild abrasives such as NuPrep are effective).•If you are using Ag/AgCl (silver/silver chloride) electrodes, put some conductive electrode paste or cream on them before applying them to the skin, or try using gel-type rather than dry Ag/AgCl electrodes.Resting EMG readings will not be affected by connection to AC power, in the following cases:•Running the MyoTrac Infiniti stand-alone, with no AC power adapter and no connection to the PC (only on its rechargeable batteries).。
Electronic Skin电子皮肤
ARTICLES
PUBLISHED ONLINE: 12 SEPTEMBER 2010 | DOI: 10.1038/NMAT2834
Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers
The development of an electronic skin is critical to the realization of artificial intelligence that comes into direct contact with humans, and to biomedical applications such as prosthetic skin. To mimic the tactile sensing properties of natural skin, large arrays of pixel pressure sensors on a flexible and stretchable substrate are required. We demonstrate flexible, capacitive pressure sensors with unprecedented sensitivity and very short response times that can be inexpensively fabricated over large areas by microstructuring of thin films of the biocompatible elastomer polydimethylsiloxane. The pressure sensitivity of the microstructured films far surpassed that exhibited by unstructured elastomeric films of similar thickness, and is tunable by using different microstructures. The microstructured films were integrated into organic field-effect transistors as the dielectric layer, forming a new type of active sensor device with similarly excellent sensitivity and response times.
GAS SENSOR
专利名称：GAS SENSOR发明人：NISHIZAWA HAJIME,SHIBATA KAZUYOSHI 申请号：JP22897986申请日：19860927公开号：JPS6382355A公开日：19880413专利内容由知识产权出版社提供摘要：PURPOSE:To achieve a higher measuring accuracy, by limiting a diffusion path route of gas which diffuses through a porous solid electrolyte body as diffusion controlled means composing an electrochemical cell to obtain a sharp characteristic curve stably. CONSTITUTION:A diffusion route of gas which diffuses through a porous solid electrolyte body 2 is limited with an airtight solid electrolytic layer 8 so that the introduction of the gas into an internal space 5 is only allowed through an opening 14 of the airtight solid electrolytic layer 8. With such an arrangement, a gas to be measured in an external space where it exists enters an internal space 5 through the opening 14 under a specified diffusion resistance, diffuses horizontally therein 5 and then, reaches a first electrode 10. Thus, the gas introduced is mixed effectively in the internal space 5 to make uniform the concentration of gas which is brought into contact with the first electrode 10 thereby stabilizing a polarization characteristic curve in a sharp form with respect to an electrochemical pump cell comprising the solid electrolytic members 2 and 8 and the electrodes 10 and 12.申请人：NGK INSULATORS LTD更多信息请下载全文后查看。
A GAS SENSOR
专利名称：A GAS SENSOR发明人：WILLIAMS, David, Edward 申请号：EP92910545.0申请日：19920518公开号：EP0591240A1公开日：19940413专利内容由知识产权出版社提供摘要： The invention relates to a gas sensor for detecting the presence of a gas in a gaseous mixture and which comprises for this purpose two pairs of electrodes (2, 3; 2, 4) mounted on a detection element (5) or in a position where the electrodes of each pair are spaced apart by a different distance or in a position where the relationship between the electrodes of one pair and the active surface of the sensor element is different for each group. In use, the ratio of the electrical resistances in the two pairs of electrodes is measured and the measured values o f this ratio are compared to a calibration curve, which shows how this ratio varies with the concentration of the gas to be detected .申请人：CAPTEUR SENSORS & ANALYSERS LTD.地址：66 Milton Park Abingdon OX14 4RY GB国籍：GB代理机构：Wendon, James更多信息请下载全文后查看。
外文翻译2(气敏传感器)
英文文献Semiconductor Gas SensorsResearch and development of gas sensors have shown great advances during the past decade. Semiconductor gas sensors mainly using SnO2 elements have been prevailing as detectors or alarms for leakage of LP (Liquefied Propane) gas and town gas, in addition to other applications. Gas sensors based on MOSFET, first proposed in 1975, have attracted interests of many researchers of many researchers, and have been developed to a point of commercialization as a hydrogen detectors. Solid electrolytes, represented by stabilized zirconia, have proven to be very promising sensors materials for oxygen, SO2,etc. This paper aims at reviewing briefly recent advances and trends in semiconductors gas sensors which were developed in a recent few years.Semiconductors gas sensors detect gases from a change in electrical resistance of an element made with a semi conductive metal oxide, typically SnO2 sensor. Although sensors utilizing γ-Fe2O3 or α-Fe2O3 have been put into practical use, SnO2 sensor still has an overwhelming market share. The production of semiconductor gas sensors has grown into a large industry: more than 5 million pieces were production in 1983.Most of them have been used in domestic homes as detectors or alarms for gas leakage. Field statistic has shown that gas alarms are quite effective to prevent an outbreak of gas leakage accident; the accident rate. Anyway semiconductors have been so far given much credit as an important device for home security and the installation rate of gas alarms is increasing year after year. Several years ago a problem arose about SnO2 gas sensor when it was adopted at places like kitchens of underground restaurants where various inflammable gases came out into atmosphere from fuels and cooking very frequently during working time. In such a dirty atmosphere, the gas sensor tended to given an alarm at an inflammable gas concentration which was lowered gradually with an elapse of operation time. It has been pointed out that the problem was contributed by electric resistance of the sensor element due to its sintering at unexpectedly high working temperatures. The problem has been solved after revisions were made to the sensor element.半导体气敏传感器在过去的十年间，气敏传感器的研究和发展已经有了很大的进步。
SCM4一款碳氧化物检测仪的说明书
010306020504070912081110Quick Start1. Install 9V battery located in the bat-tery compartment.2. P ress ON/OFF for 1 second to power on the SCM4 in a nominal CO envi-ronment such as outdoors.Note: 10 second warm up ensues.3. If necessary, press ZERO while out-doors to set the ambient CO ppm. 4. Carbon m onoxide (CO) a bove n omi-nal levels will be displayed in parts per million (ppm.)5. P ress ON/OFF for 1 second to power off.CertificationsR CM CE WEEERoHS CompliantDescription The SCM4 standalone carbon monoxide detector measures carbon monoxide in parts per million (ppm.) It is intended to measure levels of CO in still, ambient air. The most practical application of the SCM4 is to determine if the indoor CO levels are higher than outdoor levels and to determine the source. In many cases, it can help locate a source of CO.The SCM4 uses a fast reacting, electrochemical sensor that does not consume chemicals and can easily be replaced in the field if needed. Sensor life is primarily determined by the type of exposure.Precautions1. D o not measure gas engine exhaust or other high CO or highly contami-nated gases. High levels of CO and other contaminants can ruin the sensor and be a health hazard.2. Do not take readings directly in stream of air at register or in a flue.3. Allow enough time for SCM4 to reach ambient temperature and %RH.FieldpieceCarbon Monoxide DetectorOPERATOR'S MANUALModel SCM4DisplayControlsON/OFFbonoxide ectorures PPM.PRESS FOR 1 SECONDHold for one second to toggle power.SCM4ON/OFFMUTEZERO Carbon Monoxide DetectorMeasuresCO in PPM.PRESS FOR 1 SECONDAUTO-OFF BATT CHECKCancel out any ambient nomi-nal CO. (See Zero Set.)ON/OFFMUTEMAX PRESS FORAUTO-OFFToggle backlight on display.ON/OFFMUTECarbon MonoxideDetectorMeasuresCO in PPM.PRESS FOR 1 SECONDAUTO-OFF BATT CHECKMute the beep. Hold for one second to check % battery remaining.(Hold while powering ON to disable APO.)ON/OFFMUTEMAX CarbonPRESS FOR 1 SECONDAUTO-OFF BATT CHECKShow maximum measurement.How to Use"Walk Around" TestThe SCM4 responds almost instantly to changes in CO levels in the air. If you see a difference in CO levels from outside to inside, you need to find the source of the CO. Walk around and watch the display.By constantly going towards the area of higher concentration, you can determine the source of the CO.Persistent sources of CO, such as malfunctioning combustion equip-ment in occupied spaces, must be serviced immediately. These can be life threatening.When searching for sources of CO, make sure that you never put yourself or anyone else in danger of excessive exposure to CO. Overexposure to CO can have long-term health effects and can be fatal.Zero SetAs needed, set the reading to zero in a known zero CO atmosphere and in a temperature similar to the sample air to be tested. Zero only when ambi-ent air is within specifications and probe is in equilibrium (temperature and relative humidity) with ambient.To zero, hold the ZERO button for one second or until “ZER O” is dis-played. (Note: For safety reasons the SCM4 will not zero if reading is above 5ppm.)SCM4ON/OFFMUTEZEROMAXCarbon Monoxide DetectorMeasures CO in PPM.Specifications Sensor Type : Electrochemical (specific to CO)Sensor Calibration :Factory calibrated @ 17ppm CO and 200ppm CO Range :0 to 1000 ppm; 0 to 2000 ppm (less than 5 minute exposure time)Initial Accuracy : @ 73°F±9°F, <75% R.H. 0-15ppm ±5% reading ±1 ppm after zeroing 16-35ppm ±5% reading ±2 ppm after zeroing 36-1000ppm ±5% reading ±5ppm after zeroing Long Term Drift :less than 5% per year (depending on use)CO Air Sample Temperature Range : 32 to 105°FOperating Environment : 32 to 122°F (0 to 50°C);15 to 90% R.H., non-condensingStorage Environment : 32 to 68°F (0 to 20°C) at <80% R.H. with battery removed from meter.Battery : 9VBattery Life : 150 hours typical alkaline Auto Power Off : After 15 minutesStorageTo maintain sensor integrity, do not store in areas containing solvent vapors. This includes aerosols such as air-freshener, wax polish, window cleaner, and all organic solvents.ON/OFFMUTEMAXAuto Power Off (APO) Enabled Real Time CO ppm Measurement Maximum CO ppm MeasurementInstrument Muted Low BatteryCAUTION!Do not take measurements directly at a tailpipe, or at a flue. See "Precautions."Do not rely solely on a carbon monoxide measurement to determine if a heat exchanger is bad. See “CO Detectors and Cracked Heat Exchangers" section.The majority of toxic gas sensors contain sulphuric acid electrolyte and the chemical hazard is mainly related to the corrosive nature of this compound. These sensors also contain platinum, ruthenium, gold, silver, carbon some of which are toxic.Any skin or eye contact with the contents of these sensors should be washed immediately with copious amount of water. Obtain medical advice.Electrochemical gas sensors are sealed units containing an aqueous electrolyte and a combination of other sub-stances as detailed above. Provided these sensors are used only for their intended application they do not represent a chemical hazard.The sensors must not be exposed to temperatures outside the range -50°C to 60°C. Toxic gas sensors should not be exposed to organic vapours which may cause physical damage to the body of the sensor, for example 1, 2 dichloroethane.Should any sensor be so severely damaged that leakage of the contents occurs then the following procedures should be adopted.a. Avoid skin contact with any liquid or internal component through use of protective gloves.b. Disconnect sensor if it is attached to any equipment.c. Use copious amounts of clean water to wash away any spilt liquid. This is particularly important in equipment where the sensor involved contains sulfuric acid or phosphoric acid because of the corrosive nature of these electrolytes.WARNING!Extended exposure to even relatively low carbon monoxide concentrations can be hazardous to human health. Evacuate areas of significant CO concentration immediately. See the CO Exposure Effects section of this manual.131518141716192124202322CO Detectors & Cracked Heat ExchangersA CO detector can't tell you if a heat exchanger is good. A CO detector can indicate that a heat exchanger may be cracked only if all of the following conditions occur simultaneously:1. The flame must generate high concentrations of CO (lack of oxygen, excess fuel, high temp).2. Enough exhaust gases must be emitted from the heat exchanger crack.3. The exhaust gases from the crack must not be diluted too much before coming in contact with the sensor. A cracked heat exchanger may leak CO in a small stream. You may measure high concentrations at one point but low concentrations only an inch away.4. The heat exchanger must be the only possible source for the CO detected.MaintenanceClean the exterior with a dry cloth. Do not use liquid.Battery Replacement When the meter displays the battery should be replaced. Turn your SCM4 off and replace the 9V battery.Check Your Sensor:Coffee Cup CO TestTo demonstrate that your CO sensor works, turn a ceramic coffee cup upside down and slide it over the edge of a counter (or desk) to expose about a third of the mouth of the cup. Burn a cigarette lighter inside the exposed mouth of the cup. Don't burn the counter. When the flame starts to flicker, you've burned up most of the oxygen in the cup cre-ating carbon dioxide and now you're starting to produce carbon monox-ide. Bring the flame in and out of the mouth of the coffee cup to just keep the flame alive. The longer you keepthe flame flickering, the more CO you produce. After 10 seconds of flicker-ing, extinguish the flame and put the CO head in the mouth of the cup. You should see readings in the 100s. Take it out if it approaches 1000PPM.CO Sensor ReplacementThe SCM4 uses a carbon monox-ide smart sensor. If you are seeing erratic CO readings or no readings in a known CO environment, you likely need to replace the sensor.1. Obtain replacement sensor model RCM4 from your local distributor.2. Remove s ensor c ap b y r emoving t he 4 screws.3. Directly pull out old sensor.4. Hold the new sensor by the sides. While holding the sensor on the sides; press down to secure the new sensor. Do not press the new sensor from the top.5. I f the sensor is incorrectly installed, "CO Err" will be displayed and the meter will automatically shut down after 5 seconds.Sensor DisposalThe R CM4 replacement carbon monoxide smart sensor contains sulfuric as well as precious metals. The sensor should be recycled prop-erly through a local electronic waste center.Limited WarrantyThis meter is warranted against defects in material or workmanship for one year from date of purchase. Fieldpiece will replace or repair the defective unit, at its option, subject to verification of the defect.This warranty does not apply to defects resulting from abuse, neglect, accident, unauthorized repair, altera-tion, or unreasonable use of the instrument.Any implied warranties arising from the sale of a Fieldpiece product, including but not limited to implied warranties of merchantability and fitness for a particular purpose, are limited to the above. Fieldpiece shall not be liable for loss of use of the instrument or other incidental or consequential damages, expenses, or economic loss, or for any claim of such damage, expenses, or economic loss.State laws vary. The above limita-tions or exclusions may not apply to you.For ServiceIn the USA, call Fieldpiece Instru-ments for one-price-fix-all out of warranty service pricing. Send check or money order for the amount quoted. Send the meter freight pre-paid to Fieldpiece Instruments. Send proof of date and location of purchase for in-warranty service. The meter will be repaired or replaced, at the option of Fieldpiece, and returned via least cost transportation. Outside of the USA, please visit for service contact information.©Fieldpiece Instruments, Inc 2018; v10More from FieldpieceCO Exposure EffectsNote: Effects can vary significantly depending on age, sex, weight, and overall health.9 ppm Minimal. Max allowable concentration for eight hours (EPA and ASHRAE).35 ppm Max for continuous exposure for one hour (EPA and ASHRAE).50 ppm Max for eight hours (OSHA).100 ppm Trips installed CO detectors. UL2034specifies a max exposure of 100 min.200ppmIn two to three hours: slight headache, tiredness, dizziness,nausea. UL2034 specifies a max exposure of 35 min.400 ppm In one or two hours: frontal headaches. In three hours: life threatening. UL2034 specifies a max exposure of 15 minutes.800 ppm In forty five minutes: dizziness,nausea, and convulsions.800 ppm In two to three hours: death.1600 ppm In one hour: death.6400 ppm In fifteen minutes: death.12800 ppmIn three minutes: death.Combustion CheckDual-Port Manometer Accessory HeadIn-DuctPsychrometer & Air Velocity HeadFieldpieceVACUUM GAUGEENTERDigital Refrigerant ManifoldsAccessory HeadsCombustion C heck w ith A utoPumpVacuum GaugeI nc o r r e c t。
人教版高中英语选择性必修第二册课后习题 Unit 1 第一单元测评卷
第一单元测评第一部分听力(共两节,满分30分)第一节(共5小题;每小题1.5分,满分7.5分)听下面5段对话。
每段对话后有一个小题,从题中所给的A、B、C三个选项中选出最佳选项。
听完每段对话后,你都有10秒钟的时间来回答有关小题和阅读下一小题。
每段对话仅读一遍。
1.What will the woman do this coming weekend?A.Call on her classmates.B.Direct traffic.C.Go hiking.2.Where is the woman going?A.To her new flat.B.To the shop.C.To her company.3.When did the woman buy her own car?st week.st month.st year.4.What does the woman do now?A.A school teacher.B.A tourist guide.C.A university student.5.How does John look?A.Excited.B.Satisfied.C.Worried.第二节(共15小题;每小题1.5分,满分22.5分)听下面5段对话或独白。
每段对话或独白后有几个小题,从题中所给的A、B、C三个选项中选出最佳选项。
听每段对话或独白前,你将有时间阅读各个小题,每小题5秒钟;听完后,各小题将给出5秒钟的作答时间。
每段对话或独白读两遍。
听第6段材料,回答第6、7题。
6.What will the weather be like the day after tomorrow?A.It is rainy.B.It is sunny.C.It is windy.7.What has the man been doing these days?A.Reading books.B.Playing football.C.Going cycling. 听第7段材料,回答第8至10题。
Gas sensor
专利名称：Gas sensor发明人：Helmut Weyl,Claudio De La Prieta,Andreas Hachtel,Thomas Schulte,ThomasEgner,Juergen Wilde,Markus Siebert,MichaelKupzig,Uwe Glanz,Rainer Mueller,LeonoreSchwegler,Petra Kuschel,Andreas Pesch申请号：US11881639申请日：20070726公开号：US20070266735A1公开日：20071122专利内容由知识产权出版社提供专利附图：摘要：A gas sensor is for determining at least one physical quantity of a gas, e.g., an exhaust gas of an internal combustion engine, the gas sensor having a sensor element that is fixed in a housing of the gas sensor by a seal assembly. The seal assembly includes a sealing element, which has a ceramic and/or a metallic material. After the heat treatment, the sealing element has a maximum decrease in volume of 5 percent, or an increase in volume, based on the volume of the sealing element prior to the heat treatment.申请人：Helmut Weyl,Claudio De La Prieta,Andreas Hachtel,Thomas Schulte,Thomas Egner,Juergen Wilde,Markus Siebert,Michael Kupzig,Uwe Glanz,Rainer Mueller,Leonore Schwegler,Petra Kuschel,Andreas Pesch地址：Schwieberdingen DE,Stuttgart DE,Leinfelden-Echterdingen DE,StuttgartDE,Anderson SC US,Fellbach DE,Leonberg DE,Niederkassel DE,Asperg DE,Stuttgart DE,Stuttgart DE,Leonberg-Hoefingen DE,Krefeld DE国籍：DE,DE,DE,DE,US,DE,DE,DE,DE,DE,DE,DE,DE更多信息请下载全文后查看。
Toward innovations of gas sensor technology
Sensors and Actuators B108(2005)2–14ReviewToward innovations of gas sensor technologyNoboru Yamazoe∗Professor Emeritus of Kyushu University,Shimanoe Laboratory,Faculty of Engineering Sciences,Kyushu University,Kasuga-shi,Fukuoka816-8580,JapanReceived14July2004;received in revised form7December2004;accepted7December2004Available online15February2005AbstractAlthough gas sensors have been almost matured in some applicationfields,there are a variety of newly emerging markets and poten-tial markets which will be substantiated when gas sensors are innovated sufficiently.The importance of materials design in innovating gas sensors are demonstrated by taking semiconductor gas sensors and solid electrolyte gas sensors as examples.In addition,attempts to make the sensor devices more intelligent and more quantitative are also important for further advancements of gas sensor technol-ogy.©2005Elsevier B.V.All rights reserved.Keywords:Gas sensor technology;Solid electrolyte;Semiconductor;Potential marketsContents1.Introduction (3)2.Overview of the technology (3)2.1.Mature markets (3)2.2.Emerging markets (4)2.3.Challenging markets (5)3.Materials design for gas sensors (6)4.Semiconductor gas sensors (6)5.Solid electrolyte gas sensors (8)6.For innovations of gas sensor technology (11)6.1.Innovative sensors (11)6.2.Intelligent sensors (12)6.3.Hybrid systems (13)7.Concluding remarks (13)References (13)Further reading (14)Biography (14)∗Tel.:+81925837537;fax:+81925837538.E-mail address:yamazoe@mm.kyushu-u.ac.jp.0925-4005/$–see front matter©2005Elsevier B.V.All rights reserved.doi:10.1016/j.snb.2004.12.075N.Yamazoe /Sensors and Actuators B 108(2005)2–1431.IntroductionThere are a variety of gas sensors so far developed.Some sensors,such as electrolyte solution based electrochemical sensors and catalytic combustion type ones,were developed a long time ago for professional uses.A real sensor era has started in 1970s during which semiconductor combustible gas sensors,solid electrolyte oxygen sensors and humidity sensors were commercialized for non-professional uses.On the occasion of the first IMCS held at Fukuoka,Japan in 1983,major topics of gas sensors were comprised of these gas sensors.In the two decades since,extensive efforts have been compiled not only for advancing these sensors but also for developing various new gas sensors,which have been in great demand to make sure safety,health,amenity,environ-mental reservation,energy saving and so on.Fig.1shows the statistics of the whole sales of the sensors produced in Japan for the year of rge shares are occupied by groups of physical sensors,the group of gas and humidity sensors counting only 1.6%of the whole sales.Unfortunately,these statistics failed to include oxygen sensors for car emission control,which are produced in a massive scale exceeding 10million sets yearly.The real share of this group should then be considerably larger than that.Even so it is true that the gas sensors markets are still minor.Nevertheless,the importance of gas sensors for our modern society is never so minor,as easily exemplified by the importance of oxygen sensors for automobiles.Gas sensor technology has already grown to be indispensable for various aspects in our life.Yet further ad-vancements of the technology are strongly needed in order to improve sustainability of our society and quality of life.This article aims at contributing to those advancements by describ-ing the author’s personal opinions about what has been done and what is yet to be done in this field of technology.2.Overview of the technologyThe atmospheric air we live in contains numerous kinds of chemical species,natural and artificial,some of which are vital to our life while many others are harmful more orless.Fig.2illustrates the concentration levels of typical gas components concerned.The vital gases like O 2and humid-ity should be kept at adequate levels in living atmospheres,while hazardous gases should be controlled to be under the designated levels.As for lower hydrocarbons and H 2,which are used as fuels,their explosion after leakage into air is a major concern for gas sensors,and 1/10of lower explosion limit (LEL)for each gas is taken as an alarming level for gas sensors.For toxic gases,offensive odors,volatile organic compounds (VOCs)and other air pollutants,their standards have been legislated by various laws based on the strength of toxicity or offensiveness of each gas in Japan,as indi-cated by star marks in the figure.The full line shown for each gas indicates the range of concentration safely covered by a commercial gas sensor,while the broken line indicates that reportedly covered in a laboratory test.In the recent two decades,these dilute components in air have emerged as tar-gets for sensory detection,but many of them are left yet to be challenged.Some standards of VOCs such as benzene are seen to be less than 0.1ppm,far out of reach by the present gas sensors.Current trends in gas sensor technology are de-scribed in more detail below.2.1.Mature marketsWith a history of more than 3decades,markets of gas sensors have become almost mature in some fields such as combustible gas monitoring,oxygen sensing for combustion exhaust control and humidity sensing for amenity of livingFig.1.Sales of sensors for 1998in Japan [1].4N.Yamazoe /Sensors and Actuators B 108(2005)2–14Fig.2.Concentration levels of typical gas components concerned.Star marks indicate the standards of the gases legislated in Japan by (1)Environmental Standard,(2)Ordinance on Health Standards in the Office,(3)Offensive Odor Control Law,(4)Working Environment Measurement Law,and (5)Ordinance by Ministry of Health,Labour and Welfare.spaces.As a matter of course,such mature markets can be a great base for developing new sensors to replace conven-tional ones.A good example can be picked up in the field of combustible gas monitoring.This field was first opened with semiconductor gas sensors.However,catalytic combustion type gas sensors,which have been popular traditionally in Europe,have been improved to satisfy the requirements of gas alarms for combustible gases including CO in -petitions are serious in the field of CO gas monitoring where a limiting current type sensor using a proton conducting mem-brane shown in Fig.3has emerged as a second competitor.The last one is an extended version of the mixed potential type sensors for H 2and CO we reported about 15years ago [2].This sensor operates at room temperature so that it is favored by some users as a battery-driven,cordless sensor.2.2.Emerging marketsThere are several emerging markets of gas sensors as well.Fig.4illustrates how a domestic house will be equipped with gas sensors in Japan.Various kinds of sensors to monitor CO 2,air quality,odors and humidity are in increasing de-mand for various purposes.For example,a large number of air cleaners equipped with an air-quality sensor are produced yearly to be installed not only in houses but also in car cab-ins.It is noted that most of these applications are concerned with combustible gases at fairly low levels and therefore best met by semiconductor gas sensors.An auto-damper system (ADS)for car ventilation is obtained by coupling two semi-conductor gas sensors which respond to hydrocarbons and NO x (NO and NO 2),respectively.It opens or closes air inlet depending on whether the outside air is clean or polluted.AsFig.3.Structure and working mechanism of mixed potential type CO sensor operative at room temperature.N.Yamazoe /Sensors and Actuators B 108(2005)2–145Fig.4.Various kinds of gas sensors equipped at various sites in a house [3].shown in Fig.5,production of ADS is increasing year-by-year,exceeding 3millions in quantity in 2001.Yet another example is given by combination type fire alarms.Tradition-ally,fire alarms have used a smoke detector or a heat detector.In the event of fire,however,various combustible gases are also produced and those gases,particularly hydrogen,diffuse more rapidly than smoke or heat does.In many cases sensing those gases is useful for earlier detection of fire.Because of this advantage,a semiconductor gas sensor has beenincorpo-Fig.5.Annual production of auto-damper systems for cars as compared with that of cars in the world [4].rated additionally into the conventional fire alarms.Number of combined type fire alarms is increasing steeply in recent years,as shown in Fig.6.These examples indicate the high potentiality of gas sensors in our society.2.3.Challenging marketsOnce a gas sensor (seed)is developed to meet a strong demand from our society (need),a prosperous new market would be created.Numerous examples can be cited for such demands.Car emission control is going to be more and more stringent.Onboard sensors to monitor NO x ,hydrocarbons and CO are in strong demands to meet the stringent emis-sion control.The sensors are to be used not only to checktheFig.6.Annual sales of conventional type and combination type fire alarms in Japan [5].6N.Yamazoe /Sensors and Actuators B 108(2005)2–14emission levels but also to diagnose the activity of three-way catalysts.Onboard sensing of NH 3is also demanded for real-izing urea-based selective reduction of NO x .Car coolers are going to change to the ones mediated by CO 2in near future so that CO 2leakage monitoring will be demanded for safety purpose.Apart from car-related demands,monitoring of var-ious toxic or offensive compounds indoor and outdoor would become very important for securing health and amenity,as al-ready mentioned.Particularly,sensing of oxygen containing gases such as CO 2,NO x and SO 2is badly needed for various applications.In addition,special attention should be directed to the various hazardous gases present in working places.For example,N 2O and ethylene oxide gas frequently used in hospitals are beyond sensory detection at present.Various chemical reagents such as NH 3,HNO 3,HF and PH 3are used in silicon machining factories but the vapors of these reagents or their reaction products in the closed spaces are mostly left as targets of future sensory detection.From a broader view-point,we are also requested to think of ubiquitous sensors to implement the development of ubiquitous information tech-nology.All these examples indicate that our goal of the sensor development is still far away.3.Materials design for gas sensorsIn order to be used in practice,a gas sensor should fulfill many requirements which depend on the purposes,locations and conditions of sensor operation.Among the requirements,primarily important would be sensing performance-related ones (e.g.,sensitivity,selectivity and rate of response)and reliability-related ones (e.g.,drift,stability and interfering gases).These are all connected with the sensing materials used so that selection and processing of the sensing materi-als (materials design)have key importance in research and development of gas sensors.The author believes that mate-rials design is a base for new innovative sensors and thusfor innovations of gas sensor technology.Here it is tried to demonstrate this for two types of gas sensors.4.Semiconductor gas sensorsThe gas sensors using n-type oxide semiconductors like SnO 2detect gases from a change in the electrical resistance of a porous sensing body.These sensors are best suited for de-tecting combustible gases at low concentration levels in view of sensitivity,stability,robustness and so on.Despite the sim-ple working principle,however,the gas sensing mechanism involved is fairly complex.Sensing performances,especiallysensitivity,are controlled by three independent factors of re-ceptor function,transducer function and utility,as illustrated in Fig.7.Receptor function concerns the of the oxide surface to interact with the target gas.Chemical properties of the surface oxygen of the oxide itself is responsible for this function in a neat oxide device,but this function can be largely modified to induce a large change in sensitivity when an additive (noble metals,acidic or basic oxides)is loaded on the oxide surface [6–10].Transducer function concerns the ability to convert the signal caused by chemical interaction of the oxide surface (work function change)into electrical signal.This function is played by each boundary between grains,to which a double-Schottky barrier model can be ap-plied.The resistance depends on the barrier height and then on the concentration of the target gas.This situation is es-sentially unchanged with a change in the grain size (diam-eter,D )of the oxide unless D is kept above a critical value (D c )which is just equal to twice the thickness (L s )of surface space charge layer of the oxide.For D smaller than D c (6nm for SnO 2),sensitivity increases sharply with decreasing D [11–13].Since usually L s is a function of the concentration of electron donors in the bulk oxide,D c can be changed by doping the base oxide with a foreign oxide.When the oxide is loaded with a foreign additive,the additive can modify L s asFig.7.Receptor function,transducer function and utility factor as well as the physicochemical or materials properties involved for semiconductor gas sensors.N.Yamazoe/Sensors and Actuators B108(2005)2–147Fig.8.Depth profiles of gas concentration inside a porousfilm at various values of m.well if it interacts electronically with the oxide.In fact such a change in L s or barrier height explains marked sensitizing effects of certain noble metals like Pd for the sensors of this type[14–17].In the case of Pd-loaded SnO2,for example, under exposure to air Pd is oxidized into PdO,which acts a strong acceptor of electrons from SnO2.In this state,each grain of SnO2is covered with a strongly electron-deficient space charge layer,giving rise to a high resistance.Upon contact to a combustible gas in air,PdO is reduced to Pd which is no longer an electron acceptor,resulting in a sharp drop in the electrical resistance.It is noted that the sensitiz-ing effects come out through coupling a redox change of the additive with a change in its electronic interaction with the oxide grains.The last factor,utility,concerns the accessibility of inner oxide grains to the target gas.The importance of this factor is made obvious when one considers that the target gas(reduc-ing gas)reacts with the oxide surface on the way of diffusing into the balk of device.If the rate of reaction is too large com-pared with that of diffusion,the gas molecules cannot access the grains located at inner sites,leaving them un-utilized for gas sensing and thus resulting in a loss in sensor response. The existence of this factor was suspected a fairly long time ago from familiar volcano-shaped correlations between sen-sor response and operating temperature,but quantitative un-derstanding of it was made possible only recently for thinfilm devices derived from SnO2sols[18,19].When a thinfilm with pores of a uniform radius is exposed to a target gas at a concen-tration of Cs,the relative concentration(C/Cs)inside thefilm can be formulated to be,C/C s=cos h[1−(x/L)]m/cos h m,by solving a simple diffusion-reaction equation under the steady state conditions.Here,C is the concentration of target gas in thefilm,C s the concentration of target gas at x=0,x the distance from the surface,L thefilm thickness and m is a non-dimensional quantity defined by m=L(k/D k)1/2where k is rate constant of afirst order surface reaction and D k the Knudsen diffusion coefficient.As illustrated in Fig.8,theFig.9.Utility factor as correlated with m.depth profiles of concentration depend markedly on the mag-nitude of m.For m<1,significant part of target gas can reach the bottom of thefilm.For m>3,however,most part of the gas is consumed before arriving at the bottom and at extremely large m only the surface region is accessible to the gas.When the increase of sheet conductance at given x is assumed to be proportional to the target gas concentration at that point as afirst approximation,sensor response of thefilm can be derived easily by integrating the sheet conductance over the film.It is noted that the proportionality constant,called sen-sor response coefficient,used in the assumption is related to the surface reaction and thus steeply increases with increas-ing temperature.The utility factor,defined as the ratio of the sensor response to that expected under the optimal condition of m=0,can be formulated to be equal to(1/m)tan h m.As shown in Fig.9,the utility factor decreases with increasing m so that m should be kept small,or,small L and small k/D k ratio should be combined to keep the utility factor close to unity.Since D k=(4r/3)(2RT/πM)1/2,where r is pore radius, M the molecular mass of target gas and RT has its usual mean-ing,thefilm has to have r as large as possible and L as small as possible to obtain higher utility factor.This is in agree-ment with the experimental result that the responses of SnO2 thinfilms to H2decreased with increasing L[18].Further,r is known empirically to be roughly comparable to the size (D)of grains involved so that the utility factor can also be controlled through D.Strikingly sharp dependence of sen-sor response on the grain(crystallite)size has been observed for H2S,which is seemingly more susceptible to a change in microstructure than H2,as shown in Fig.10[20].It would be of interest to consider how the volcano-shaped correlation between resistance and temperature appears.The sensor response under optimal condition(m=0)tends to in-crease with increasing T because the sensor response coef-ficient increases.The utility factor,on the other hand,goes down with increasing T,eventually approaching to zero at sufficiently high T,because the term k/D k increases sharply to take a very large value at high T.The volcano-shaped8N.Yamazoe /Sensors and Actuators B 108(2005)2–14Fig.10.Sensor responses to 5ppm H 2S for the thin film devices derived from SnO 2sols different in crystallite size as correlated with operating tem-perature (constant film thicknesses of about 200nm).correlation results when these phenomena are coupled to-gether,as simulated for different film thicknesses in Fig.11[18].Apparently the temperature at the response maximum can be taken as a measure to estimate the openness of mi-crostructure.These results indicate how important the mi-crostructure control is for promoting the sensor response of a thin film device.For a thick film device or a bulk type de-vice,microstructure is more complicated with the presence of secondary particles of grains and macro-pores.Nevertheless,almost the same conclusions can be drawn for these devices if L is redefined as the radius of secondary particles involved.More complicated situation prevails for the devices loaded with foreign additives where all of the three independent fac-tors mentioned before should be optimized.Even in such a case,however,the importance of microstructure control re-mains intact.For instance,the sensor response to CO for a thick film device using Co 3O 4(0.5mass%)loaded SnO 2goes through a fairly sharp maximum on increasing mixing time in a satellite ball mill for the composite prior to screen-printing,as shown in Fig.12[21].The sensor response aftermixingFig.11.V olcano-shaped correlations between sensor response and operating temperature simulated for thin film devices different in filmthickness.Fig.12.Sensor responses to 100ppm CO for Co 3O 4(0.5wt.%)-SnO 2com-posite thick film devices as correlated with the time of ball-milling.the optimum time is about 1000to 100ppm CO,which is al-most two orders of magnitude higher than the highest values so far achieved with various devices.As evaluated form the pore size distribution analysis for the powder samples,the volume of pores in the radius range of 10–35nm increases in the initial mixing time up to 6h.This suggests that the pro-motion of sensor response is brought about by the increase of porosity,though the deterioration of sensor response with the later mixing is yet to be investigated.Optimization of higher order structure for a composite system would be one of the most important subjects in the research and development of gas sensors for very dilute components like benzene.5.Solid electrolyte gas sensorsIn recent years,one of major topics in solid electrolyte gas sensors has been research and development of type III sensors for which an electrochemical cell made of a typical solid electrolyte like NASICON (Na 3Zr 2Si 2PO 12,Na +conductor)which is attached with an oxyacid salt like Na 2CO 3as an auxiliary phase (foreign receptor).The devices of this type were first proposed for detection of SO 2and CO 2by the group of Saito and co-workers [22,23].For example,the CO 2sensor was constructed as follows.•Ambient air,Au |NASICON |Na 2CO 3|Au,CO 2in air;•Sensing electrode reaction:2Na ++CO 2+(1/2)O 2+2e −=Na 2CO 3•Reference electrode reaction:2Na ++(1/2)O 2+2e −=Na 2O(inNASICON)•Overall reaction;Na 2O (in NASICON)+CO 2=Na 2CO 3Upon exposure to CO 2of partial pressure P CO 2,theoret-ically this cell generates electromotive force (EMF)accord-N.Yamazoe/Sensors and Actuators B108(2005)2–149ing to the Nernst’s equation,EMF=E0+(RT/2F)ln P CO2, when the oxygen partial pressures over the sensing and reference electrodes are the same.Here F is Faraday constant and RT has the usual meaning.E0is a constant which is de-termined by chemical activities of Na2O(in NASICON)and Na2CO3.Obviously the sensor forms a galvanic cell(trans-ducer)by combining a CO2-sensitive half-cell(right)with an O2-sensitive one(left).Similarly a sensor for NO2and SO3(or SO2)can be formulated easily by replacing NA2CO3 by NaNO3or Na2SO4,respectively.Although these devices work reasonably well under ideal conditions at elevated oper-ating temperatures,gas-sensing properties become unstable under humid conditions.Because of such weaknesses,none of these sensors have been put in practice,in spite of the inten-sive research efforts devoted.From a viewpoint of practical devices,both of the half-cells should be improved substan-tially,as described mainly for the case of CO2sensors below.As for the auxiliary phase used for the gas-sensitive half cell in CO2sensing devices,we found that binary systems between Na2CO3and alkaline earth metal carbonate such as Na2CO3–BaCO3(1:2in molar ratio)were superior to the neat phase of Na2CO3[24,25].When the auxiliary phase was attached to the surface of NASICON disk by a melting-and-quenching method,Na2CO3was found to corrode the NASI-CON surface very seriously,while the binary systems were far less corrosive.In addition,the binary systems made it pos-sible to obtain afine,porous layer of auxiliary phase,which was beneficial indeed for quick responses of the devices to CO2.The devices exhibited excellent CO2sensing perfor-mances without being disturbed by humidity under steady operation at elevated temperatures(400–500◦C).Unfortu-nately,however,these devices turned out to be totally im-practical because the auxiliary phases containing Na2CO3 were too deliquescent at room temperature to survive in hu-mid atmospheres;once kept switched off overnight in hu-mid atmospheres,for example,the devices lost the sensing capability almost completely.Fortunately it was found that Li2CO3,non-deliquescent carbonate,could replace Na2CO3 and that the binary systems including it like Li2CO3–BaCO3 (1:2in molar ratio)gave excellent CO2sensing properties at elevated temperature as well as good stability in humid atmospheres at room temperature[26,27].Such material de-sign was also essential for developing type III sensors for SO2 [28–30]and NO2[31–34].Gas sensing capabilities of some of type III sensors developed in our laboratory are shown in Fig.13,together with the solid electrolytes and auxiliary phases used.For the SO2sensor,a ternary system auxiliary phase including SiO2was useful to improve adhesion of the auxiliary phase to the substrate of magnesia-stabilized zir-conia(MSZ).For the NO2sensor,NaNO2was found to be a far better auxiliary phase for detecting low concentrations of NO2than NaNO3[32,34].Especially a binary compos-ite NaNO2–Li2CO3(9:1in molar ratio)made it possible to extend lower detection limit(LDL)down to5ppb or below [34].It is remarked that each type III sensor exhibits EMF in air(base EMF),which is most probably the response tothe Fig.13.Sensing capabilities of type III solid electrolyte sensors to CO2, NO2or SO2at respective operating temperatures indicated. concerned target gas dissociated thermally from the auxiliary phase used.Optimization of the auxiliary phase to lower the base EMF is thus a way to improve LDL.It is concluded that the auxiliary phase determines all the important properties to respond the target gas(receptor function).Improvement of the reference half-cell was found to be also indispensable for the devices using NASICON solid electrolyte.It has been revealed that NASICON is vulnerable to attack by humid air at ambient temperature,eluding out the Na3PO4impurity present at grain boundaries to be deposited on the surface as shown in Fig.14.In the presence of CO2, this impurity can act as a source to derive Na2CO3,which provides the reference electrode with CO2sensing proper-ties and thus deprives the devices of gas sensing capabilities. In addition,it is also possible in the presence of humid air and CO2that the Na2O component in NASICON reacts with CO2to result in a decrease in its activity,which is also unfa-vorable for the reference half-cell.These phenomena are not visible during steady sensor operation at elevatetemperature Fig.14.Deposits spontaneously formed on the surface after a NASICON disk was kept in humid air containing CO2at ambient temperature for a long time(13days).10N.Yamazoe /Sensors and Actuators B 108(2005)2–14Fig.15.Stability of glass-coated NaCoO 2electrode and conventional Au electrode during a series of heat-cycle tests as observed with a three-electrode device indicated.but become conspicuous as a drift in base EMF or a loss of CO 2sensing properties when the devices are kept at room temperature in humid atmospheres.In order to overcome this problem,the reference half-cell should be improved to be resistant to the change of NASICON surface.In principle,this is achieved by introducing either an oxide ion conductor such as BICUBOX [35]or a solid reference material such as Na 0.6CoO 2(cobalt bronze)[36]between the reference elec-trode and NASICON to construct a new reference half-cell as follows:•Ambient air,Au |BICUVOX or Na 0.6CoO 2|NASICON The former material would allow the half cell to be fixed at the potential determined by the partial pressure of oxygen (air reference),while the latter would to that de-termined by the electrode reaction of the material itself,x Na 0.6CoO 2=x Na 0.6−1/x CoO 2+Na ++e −,(solid reference).Actually the latter material turned out to be unstable to the attack by CO 2as it was.Fortunately however,it could be sta-bilized effectively when coated with a layer of an inorganic glass.Both of the above materials were effective in stabiliz-ing the EMF response to CO 2from drifting even after the devices were exposed to humid atmospheres at room tem-perature.Fig.15compares the behavior of the glass-coated Na 0.6CoO 2with that of a bare Au reference electrode during a heat cycle test;Temperature was switched between operat-ing temperature (450◦C)and room temperature at intervals of one to several days,while,under a fixed concentration of CO 2,humidity of the gas flow was altered stepwise at inde-pendent intervals as shown.For this test,a three-electrode device was fabricated as also shown and the potential of each electrode was measured relative to the third electrode (Au)which was always exposed to clean synthetic air.It is seen that the potential of the bare Au electrode continued to float up and down during the heat-cycle test,reflecting the instability of the NASICON surface.On the other hand,the potential of the other electrode tended to converge to a steady value after an ageing period in the beginning,confirming its reliability as a reference electrode.From the same figure,the potential of this electrode is seen to reach the steady value quickly at the heating up stage.Such fast warm-up characteristics are requested especially for applications to non-stationary facil-ities like cars.It is remarked that the introduction of a solid reference material should be also important for the NO 2sen-sor using NASICON as well,though this is yet to be verified.Conventionally the sensing electrode for type III CO 2sen-sors is provided with metals such as Au.When the metal electrode is replaced by an oxide electrode such as indium-tin-oxide (ITO),utterly different CO 2sensing properties are obtained.That is,the device fabricated as shown in Fig.16exhibits excellent CO 2sensing performances at room temper-ature (30◦C)in the presence of humidity at 30%and above in relative humidity,as shown in the same figure [37].In this device,the same auxiliary phase as used previously is located between NASICON and a porous layer of ITO,while the Au reference electrode is covered with a layer of an inorganic adhesive.The sensing electrode reaction involving CO 2in this case appears to be mediated by adsorbed water on the。
GAS SENSOR
专利名称：GAS SENSOR发明人：NAKAMOTO HIDEKAZU,KATOU KAZUO,AIHARA MAKOTO申请号：JP8812181申请日：19810610公开号：JPS57203938A公开日：19821214专利内容由知识产权出版社提供摘要：PURPOSE:To enable the detection of gas regardless of the displacement in the position of an intermediate electrode or lost balance between right and left metal oxides by arranging a heat doubling a first electrode, an intermediate electrode and a second electrode sequentially on a semiconductor section with a radiation plate provided on an intermediate electrode. CONSTITUTION:A heater 3 doubling a first electrode, an intermediate electrode 10 and a second electrode 5 on a semiconductor section 2 made up of a metal oxide of SnO2 sequentially from one end thereof. A radiation plate 11 is provided on the intermediate electrode 10. The temperature near the intermediate electrode 10 becomes such a low temperature to increase a gap between a difference in the temperature between the heater 3 and the intermediate electrode 10 and that between the intermediate electrode 10 and the second electrode 5. This enhances the voltage difference amount between an output voltage VH at a high temperature section between the heater 3 and the intermediate electrode 10 and an output voltage VL at a low temperature section between the intermediate electrode 10 and the second electrode 5.申请人：HITACHI SEISAKUSHO KK更多信息请下载全文后查看。
Gas sensor capsule
专利名称：Gas sensor capsule发明人：Kalantar-Zadeh, Kourosh,Berean, Kyle,Ha, Nam,Ou, Jian Zhen申请号：AU2017311852申请日：20170814公开号：AU2017311852A1公开日：20190221专利内容由知识产权出版社提供摘要：A capsule adapted to be introduced into the digestive system and gastrointestinal (Gl) tract of a mammal which consists of a capsule shaped container consisting of a wall material capable of being bio compatible with the digestive system and being adapted to protect the electronic and sensor devices contained in the capsule. The capsule contains gas composition sensors operable at several temperature points for a short duration, a temperature sensor, a micro controller, a power source and a wireless transmission device. The capsule wall incorporates gas permeable membranes adjacent said gas sensors. The microprocessor is programmed to receive data signals from the sensors and convert the signals into gas composition and concentration data and temperature data suitable for transmission to an external computing device.申请人：Royal Melbourne Institute of Technology代理人：FPA Patent Attorneys Pty Ltd更多信息请下载全文后查看。
GAS SENSOR
专利名称：GAS SENSOR发明人：BESSHO YOSHINORI 申请号：JP27938289申请日：19891026公开号：JPH03140838A公开日：19910614专利内容由知识产权出版社提供摘要：PURPOSE:To measure the amount of gas with high resolving power on the basis of the frequency change of a surface elastic wave element by detecting the phase difference between the first and second synthetic signals as the change quantity of frequency of a surface elastic wave. CONSTITUTION:The resonance frequency of a surface clastic wave element 10 is changed by frequency DELTAf from reference resonance frequency fP by the adsorption of gas due to an adsorbing membrane 16 and a measuring signal changed by frequency (fP-DELTAf) is detected by a detector 10b to be outputted. The first reference signal (frequency fR) whose frequency is slightly different from the reference resonance frequency fP and the measuring signal are synthesized by the first synthesizing means 32 to fetch the first synthetic signal changed by the difference frequency (fP-fR-DELTA) of those frequencies. The second reference signal whose frequency is equal to the frequency fP and the first reference signal are synthesized by the second synthesizing means 34 to fetch the second synthetic signal changed by the difference frequency (fP-FR) thereof. Then, first and second synthetic signals is detected by a phase difference detection means 36. Next, the amount of the gas adsorbed on the adsorbing membrane can be measured on the basis of the phase difference with high accuracy.申请人：BROTHER IND LTD 更多信息请下载全文后查看。
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Gas conductive sensor technology and applicationYou Ke , Chang Min HuiBeijing Union University, Beijing, Chinayouke@ ,xxtminhui@Abstract—In this paper, a kind of general gas-conductive sensor is proposed. Gas-conductive sensor Based on ZigBee technology ,the model employs star topology and STOP mode. The efficiency of the new model is reducing the power consumption of each sensor node and meanwhile lengthening its life-span. Furthermore, the security and reliability of the system are greatly improved because of the Cyclic Redundancy Check and the encryption algorithm’s application.Index Terms—Gas-Conductive; Sensor; Pressure;I.P REFACEGas sensor is a device that may perceive a certain gas and its concentration in the ambient. The sensor convert the information in relation with gas type and concentration into electrical signals, by analyzing the electrical signals, we may acquire the information relevantto the existence nature of the tested gas in the environment, so as to perform detection, monitoring and alarming. Through interface circuits, the sensors may constitute automatic detection, control and alarm system with computer, so as to create a highly functional environmental monitoring system. This sensor architecture features advantages such as high measurement accuracy, less sample and prompt response, and enjoys extensive applications.II.W ORK PRINCIPLE OF GAS SENSORThe work principles of gas sensors may include semiconductor type, contact burning type, chemical reaction type, light interference type, thermal conduction type, IR ray adsorption type, etc. This article will focus on the work principles of popular semi-conductor gas sensor and solid electrolyte gas sensor.Semi-conductor gas sensor is comprised of detector, heating coil and blast protection screen, in this type of gas sensor, sensitizers such as Pt and Pd are added into metal oxides such as SnO2, Fe2O2 and ZnO2. Refer to Figure 1 for constitution of SnO2 series gas sensor. The selectivityof gas sensor is determined by the dosage of sensitizer, for example, for ZnO2series sensor, if Pt is added, then the sensor will be more sensitive to propane and isobutene; if Pd is added, the sensor will be more sensitive to CO andH2.SnO2 is a material with poor sintering tendency and high thermal stability. This type of sensor may only host reversible oxidation reactions on the surface of semi-conductor, while the chemical structure inside the semi-conductor will remain unchanged, to this end, high stability may be achieved even after long term use. SnO2is widely used in most cases of application. The work principle is as follows: when SnO2 is being heated, the oxygen in the air may bore off electrons from the donor level of SnO2 crystal particles, while negative electrons are attached on the surface of crystal, resulting in an increase of surface potential and subsequent blocking of the movement of conduction electrons. Hence, the gas sensor may present a constant resistance in the air. At this time, reducing gas form oxidation reaction with the oxygen adsorbed on the surface of semi-conductor, isolation effect of gas molecules results in the change of surface potential, consequently the resistance of sensor may change. For reducing gas, resistance reduces; for oxidizing gas, resistance increases. In this way, gas concentration may be detected by measuring the change of resistance.Construction of electrochemical solid electrolyte CO sensor is shown in Figure 2. It uses solid electrolyte to overcome strong acid electrolyte solution leakage and the necessity of frequent addition of electrolyte solution. The replacement of electrolyte solution by solid electrolyte is being studied. Solid electrolyte sensor uses inorganic salts such as Zr02, Y2O3, KAg4I5, K2CO3 and LaF3 as solid electrolyte, the solid electrolyte and electrodes. The pure solid electrolyte may conduct ion, but it can’t conduct electron, at the same time pure solid electrolyte features very low conductivity. To this end, high temperature ambience is usually required, this may be realized by installing internal heater. The solid electrolyte ZrO2 is mainly used for oxygen sensor, and can also be used for detection of CO. Due to the very low conductivity of inorganic salt solid electrolyte in low temperature and the electrolyte operates by potential difference and being insensitive to slight temperature change, and vulnerable to interference of other gas. Hence, CO detection in complicated sites is not recommended.III.A PPLICATION TECHNOLOGY OF GAS SENSORA.How to improve performance of gas sensorGas sensor’s life is limited and it is vulnerable to the influence of coexisted gas so it requires timely calibration. To this end, measure should be taken to improve the performance of sensor.1)Improve the sensitivity of gas sensorThere are allowable concentration regulations for various gas issued by environmental and health authorities. In recent years, highly toxic gas has been in more frequentISBN 978-952-5726-00-8 (Print), 978-952-5726-01-5 (CD-ROM) Proceedings of the 2009 International Symposium on Web Information Systems and Applications (WISA’09)Nanchang,P.R. China, May 22-24, 2009,pp.541-543Figure 1. Constitution of Sn02 Series Gas Sensorus. So it is expected that the sensitivity of gas sensor may be increase so it may detect a gas concentration lower than 10%.2) Reduce the influence of coexisted gasGas emission of ordinary plants may include the tested gas and many coexisted gases. So it is expected that the gas sensor in operation may not subject to the influence of coexisted gas.3) Longer sensor lifeLife of existing gas sensors varies from 6 months to 3 years as per the type of tested gas, electrolyte solution and shape. It is expected that the minimal life of sensor may be extended to at least one year. 4) Calibration-freeGas sensor needs to be calibrated by using calibration gas, the calibration frequency may vary from 6 months to 1 year per different types of gas. For water soluble gases such as HCL and HF, calibration is rather difficult to handle. So it is expected to use the gas sensors that doesn’t require calibration.5) Extend the scope of operation environmentTake certain measures on preset potential, electrolyte material and electrode material may help to improve the sensitivity to gas, and reduce the influence of co-existed gas. Currently electrode is primarily made of Pt, Au and Pd, by using new electrode materials may improve the selectivity of coexisted gas and improve the sensitivity of the detected gas.In addition, chemicals may also be used to remove the co-existed gas, in other cases, the electrical property difference of sensors may also be used to reduce the influence of coexisted gas.The gas emission from semi-conductor plants contains many types of gases. In order to detect as many types of gases as possible, the gas sensor being sensitive to multiple types of gas may be used.In order to prolong the service life of sensors, efforts should be taken on sensor construction and materials so as to prevent the evaporation of electrolyte solution in high temperature, materials with high temperature resistance should also be developed.B. Gas sensor output voltage acquiring methodSemi-conductor gas sensor adopts heater to warm up the detection element, at this time, the heating temperature of the heater has profound influence on the gas sensor’s property. To this end, the voltage stability is vitally important. In addition, the consumption power of the gas sensor should not exceed the rating, otherwise the detection element might be damaged.The gas sensor’s output voltage acquiring pattern is shown in Figure3.On that Figure, Figure (a) is a resistorR S in series with gas sensor, the voltage reduction at R S is then the output voltage of the sensor. If harmful gas is detected, resistance of the detection element may decrease. At this time, the voltage on both sides of R S may increase, consequently, the output voltage may change. R S is determined by the resistance of the detection element corresponding to a certain gas concentration. For ordinary applications, when the sensor output voltage is 2～3V, the processing of subsequent circuit may be very convenient. In Figure (b), the sensor output is connected with the same phase input of comparator A 1. When the gas concentration exceed the preset value, A 1 will give high level, so a simple gas detection circuit is constituted.Furthermore, semi-conductor gas sensor’s resistance in gas is in relation with temperature and temperature, to this end, in different temperatures, the same gas concentration will bring about different resistance, so compensation is required. Figure (c) is a simple temperature compensation circuit. Connect negative temperature coefficient thermal resistor R T is connected with reverse phase input end(reference voltage end), when temperature decreases, R T value increases, so the reference temperature decreases; when temperature increases, reference voltage also increase, so the temperature deviation is compensated. Material constant of thermal resistor is determined according to the temperature dependence of gas sensor, ordinarily, the selected material constant is 3700~4000 thermal resistor, that may provide temperature compensation to many semi-conductor gas sensor. However, when using thermal resistors, effective compensation can not be achieved in both high and low temperatures, at this time, when gas is detected, low temperature compensation should beconsidered as a priority.IV. E XAMPLE OF GAS SENSOR APPLICATION Figure 4 is a linear circuit of gas sensor. When detecting CH 4 concentration, perform indirect heating on CH 4 gas sensor by current I H =167mA, the CH 4 concentration equivalent resistant R S will tend to reduce non-linearly along with the increase of gas concentration. The typical example is that when CH 4 concentration=l000ppm, R S =14.0K Ω; when CH 4 concentration =l0000ppm 时，R S =4.2 K Ω. If the current through R S remain constant(I=0.5mA), then voltage V T =IRS will indicate CH 4concentration.Figure 2. Construction of Electrochemical Solid Electrolyte CO Sensor(a)Output voltage (b)Simple gas (c)Simple temperatureacquiring pattern test circuit compensation circuitFigure 3. Gas sensor output voltage acquiring patternWhen V T passes linear circuit AD538 and amplifier A 3, output voltage V OUT is obtained. V OUT is linear to CH 4 concentration. In the Figure, REF-03 provides reference voltage and generate constant current I=0.5mA. A 1 plays isolation role, A 3 plays buffering role.When adjusting the sensor, place the sensor in a room whose volume is already known, then feed in the room CH 4 gas to the pre-determined concentration (1000ppm), and use fan to mix. Adjust resistor R 1, set the output U O to l.0V, then increase CH 4 concentration to 10000ppm, adjust resistor R 6, set the output U O to 10.0V. Repeat adjustment till satisfaction is achieved.Figure 5 shows a gas monitoring circuit using AF30L as sensor. AF30L/38L is a type of semi-conductor gas sensor whose detection element resistance may change per the oxidation/reduction reaction on its surface, the sensor is applicable to detection of smoke and odor, etc. The heating coil voltage is AC or DC 5V±0.2V, theconsumption power 300mW, service temperature -10℃～+55. In the ℃Figure, 7805 provides AF30L with +5V stable voltage, its heating may influence the property of AF30L, so AF30L should be installed at a location far away from 7805. A 2 and other elements constitute relay circuit to prevent the possible misoperation cased by the instable sensor resistance at start-up. When the circuit isstarted, capacitor C 3 subject to a 0 voltage, A 3 output low level, VT 1 is cut off, even though VT 3 is connected due to sensor misoperation, relay K will not operate; after a certain relay time(determined by R 5 and C 3 value), C 3 is fully recharged, A 2 output high level, VT 1 is in connection status. A 1 is a comparator, RP 2 adjust the preset voltage. When the detected gas is clean, the resistance between electrode A and B of AF30L is high, the in-phase input side voltage of A 1 is lower than that of the anti-phase (preset value), A 1 output low level,VT 1 cuts off, relay K doesn’t operate. When the detected gas concentration surpasses the pre-set value, the resistance between electrode A and B, the in-phase input side voltage of A 1 is higher than that of the anti-phase input side, A1 outputs high level, VT 1 is connected, relay K is activated and start up the blower fan, so the function of monitoring is achieved.Figure 6 shows a smoke monitoring circuit using AF38L. the output of gas sensor AF38L passes through A 1 voltage follower and reaches the in-phase input side of differential amplifier A 2, A 2 output is amplification of voltage differential between the in-phase input and anti-phase output. A 3 is in-phase amplifier, gain factor of A 3 may be adjusted through RP 3, in another word to adjustthe in-phase input side voltage of A 4～A 8 comparator. In this way, the number of illumination among LED 2～LED 6 may be determined to indicated the level of air pollution so as to control smoking.V.C ONCLUSIONThis article introduces work principle and voltage acquiring pattern of a type of gas sensor. Compared with traditional sensors, this sensor enjoys advantages such as higher measurement accuracy, less sampling and prompt response and is expected to be used widely. By directly using or slightly modifying the gas sensor application examples, the gas sensor may be used in environment monitoring and control circuit, in order to constitute a high quality monitoring systemFigure 4. Linear circuit of gas sensorFigure 5. Gas monitoring circuit using AF30LFigure 6. Smoke monitoring circuit using AF38L。