电容层析成像

电容层析成像（ECT）

电容层析成像技术（ECT，Electrical Capacotance Tomography）是过程层析成像技术（PT，Process Tomography）的一种，是20世纪80年代后期在医学CT技术基础上形成和发展起来的。原理是根据被测物质各相具有不同的介电常数，当各相组分分布或浓度分布发生变化时，将引起混合流体等价介电常数发生变化，从而使测量电极对间的电容值发生变化，在此基础上，利用相应的图像重建算法重建被测物场的介电分布图。

ECT因具有快速、无损、廉价，灵活，兼容标准软件等优点而被认为是一种具有广阔发展前景的过程成像技术。电容层析成像技术在国内现处于实验室研究阶段，离工业应用还有一段距离，上海沃埃得贸易有限公司引入了英国、美国两家供应商提供的仪器来满足国内各高校、研究所的不同需求。

1. ECVT Data Acquisition System:

●Unique capacitance sensor with up to 36 plates

●DAS-2 intermediary device between sensor and host PC

●USB connection to host PC

●All analysis and reconstruction occurs on PC

2. ECVT Sensors:

●Capacitance plates wrapped around vessel inside sensor housing

●Common sensors have 12, 24, or 36 plates

●Plates connect to DAS-2 with RF cables

3. Data Acquisition System-2

●Drives AC signals to and receives measurements from capacitor plates

●Uses USB to communicate with host computer

●Dynamic Link Library usage

●5-Volt power source

●Download software on CD to host PC

●ECVT plate connections in groups of 6

●Three 12-plate receiver cards may be installed

●LEDs indicate power, run, and calibration status of DAS-2

●Capacitance Reading Range: 1.1 fF (10-15 F) to 11 pF (10-12 F), 1 fF resolution

●Relative Permittivity Range: 0.01 to 100 (Dynamic ratio of 1 to 10,000)

●Typical Measurement Time: 18.1 μs (10-6 s)

●For 24-plate setup, typical operating speed is 200 frames/second

●Receiver cards work in parallel to increase speed