三电极体系

Three-Electrode potentiostat
2018/12/17
Question
Why add the auxiliary electrode?
2018/12/17
2018/12/17
三电极由工作电极，参比电极，辅助电极（或对电极 ）组成。三电极体系含两个回路，一个回路由工作电 极和参比电极组成，用来测试工作电极的电化学反应 过程，另一个回路由工作电极和辅助电极组成，起传 输电子形成回路的作用。也就是说，工作电极的电位 是相对于参比电极，而对电极与工作电极是组成一个 2018/12/17 电路的闭合回路
三电极电化学传感器在化学、生物和环境监 测等领域的应用越来越广泛,为了充分发挥其性能 ,并实现测量仪器的便携性,选用AT89S8252单片机 和A /D、D /A转换器等IC芯片,设计了一种用于传 感器电流信号检测的便携式恒电位仪。该恒电位 仪通过电压负反馈调节系统使电化学传感器的工 作电压等于基准电压,并保持恒定。为检测仪器的 性能,用一个电路模型等效三电极电化学传感器进 行了测试,实验结果表明该恒电位仪具有很好的精 度。
2018/12/17
恒电位仪就是用来维持工作电极和参比电极间电位差 恒定的电子设备,其中控制部分的精简电路。图中把 工作电极接实地,可以防止寄生信号的干扰,从而提高 了电路中电流和电压的稳定性和精度。这样,恒定电 位就变成了保证参比电极没有电流流过的前提下,其 电位恒定在某固定值。把参比电位加到控制放大器 (CA)的反相端,在CA同相输入端加控制电压作为基准 电位,控制放大器的输出端接辅助电极形成闭环负反 馈调节系统。反相输入端的电位随同相输入端的电位 变化而变化,因此当同相端的基准电位恒定时,电极中 电流变化时,参比电位相对于工作电极电位的任何微 小变化,均将为电路的电压负反馈所纠正,从而达到自 动恒定电位的目的。 2018/12/17
三电极体系组成
The three electrode is made of working electrode, reference electrode, auxiliary electrode (or electrode).. Three electrode system containing two loop, a back route of working electrode and the reference electrode composition than, used to test the working electrode of electrochemical reaction process, another return route working electrode and auxiliary electrode composition, electron transport to form a loop. That is, the potential of the working electrode is relative to the reference electrode, while the electrode and the working electrode are the closed circuit of a circuit
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如果直接在工作电极和参比电极间加电压,在电 压的作用下,工作电极表面产生化学反应。由于 此时工作电极和参比电极间形成回路,反应所产 生的电流将通过参比电极输出,随着反应电流的 变化,工作电极和参比电极间的电压也会发生改 变,无法保持恒定。加入辅助电极,就是要通过 反馈作用使工作电极和参比电极间的电压保持 恒定,保证参比电极没有电流流过,强迫反应电 流全部通过辅助电极输出
电极电化学传感器通过在工作电极和参比电极间加控 制电压,在工作电极表面产生电流信号,该电流信号与 被测物质浓度具有一定的关系,分析该电流信号就可 以算出被测物的浓度。实际进行信号处理时,需要在 工作电极和参比电极间加一个恒定电位,以维持传感 器的电化学稳定性,使其能稳定地输出模拟信号。因 此,恒电位仪是电化学传感器不可缺少的设备。
三电极体系
120703021232 应化2班 谭拥
2018/12/17
Abstract
Three2electrode electrochemical sensor is used in the area of chemical, biology and environment detecting. To takefull advantage of the performance of sensor and to achieve the portability of the detecting instrument, AT89S8252 SCM and ICchip s such asA /D, D /A converterwere selected for the design of a portable potentiostat to detect the signal of the electric current.The potentiostatmakes the working voltage of the electrochemical sensor a constant and equal to the reference voltage by the voltagenegative feedback adjusts system. To test the performance of the instrument, a testingwas carried out using a circuitmodelwhichis equivalent to the three2electrode electrochemical sensor. Thwk.baidu.com experimental result shows that the instrument has 2018/12/17 good accuracy
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The three electrode electrochemical sensor includes working electrode (WE), reference electrode (RE) and auxiliary electrode (AE).. We produce a chemical reaction on the electrode surface; re in no current through the, used to maintain the working electrode and the reference electrode voltage constant; AE is used to produce the output response of the current signal, by the measuring circuit achieve signal conversion and amplification.
原理
三电极电化学传感器包含工作电极(WE) ,参比电 极(RE)和辅助电极(AE) 。WE的作用是在电极 表面产生化学反应;RE在没有电流通过的前提下 ,用来维持工作电极与参比电极间电压的恒定 ;AE用来输出反应产生的电流信号,由测量电路 实现信号的转换和放大。
2018/12/17
Three-Electrode potentiostat
三电极体系
1 工作电极 2 参比电极 3 辅助电极
2018/12/17
Through a three electrode electrochemical sensor in the working electrode and the reference electrode than with the control voltage, on the surface of the working electrode to produce current signal, the current signal and measured the concentration of a substance has a certain relationship, analysis of the current signal can be calculated the analyte concentration. When signal processing is actually carried out, it is needed to add a constant potential between the working electrode and reference electrode, so as to maintain the electrochemical stability of the sensor, so that it can output analog signal stably.. Therefore, the constant potential instrument is the indispensable equipment of electrochemical sensor