Research Of Equivalent Circuit For Three-Electrode Electrochemical Sensors

At the present time, simulation is a very important step of the circuit design process. Because it can not only shorten the development time, but also reduce the cost of the study. So it's important to design the equivalent circuit model of the sensors for simulation.The equivalent circuit model must be able to reflect the characteristics of the electrochemical sensors, and also can be used for simulation. At present, the equivalent circuit model of the sensor is mainly used for the analysis of the electrochemical reaction mechanism in chemistry. And in electrics, the researchers use a general simplified equivalent circuit model, which can not reflect the specific characteristics of the sensor very well.So, it is necessary for us to develop a specific equivalent circuit model for the boron-doped diamond film electrode used on the COD on-line monitor.Summarizing the research of the equivalent circuit model of the sensors in chemistry and electrics, we develop the equivalent circuit model of the electrochemical sensors for simulation using the AC impedance analysis.Firstly, to ensure the quality of the BDD film electrode, we test its electrical and chemical properties.Secondly, we obtain the AC impedance data through the AC impedance experiment, and get the preliminary model using Zview. Thirdly, we transform and simplify the equivalent circuit model through frequency domain analysis, and get the low-frequency and high-frequency models respectively. Fourthly, we analyze the characteristics of the equivalent circuit components and summarize the variation. Finally, we simulate the DC operating point of the potentiostat with the low-frequency equivalent circuit model, and simulate the stability with high-frequency model.Comparing the simulation and experimental results, we can conclude that the equivalent circuit model can reflect the characteristics of the sensor very well, and it can be used for simulation as a good equivalent alternative.We develop the equivalent circuit model for the three-electrode electrochemical sensor with the BDD film electrode as the working electrode. The error between the simulation and experimental results is 7.02%, showing that it is a good and effective alternative.