Design And Realization Of Ampere Detection Circuit For Microfluidic Capillary Electophoresis

Recently,Japan's decision to discharge wastewater from the Fukushima nuclear accident has aroused deep discussions on the issue of water pollution.The heavy metal pollution of water in my country is serious.Monitoring and detecting the content of heavy metals in water is the top priority of water pollution.This project aims to design an amperometric detection circuit that is easy to carry and can detect multiple heavy metal ions in real time.The microfluidic chip is a micro-scale chip that integrates functions such as chemical analysis and biological detection in a multi-disciplinary cross.It has the characteristics of miniaturization and has higher advantages than traditional detection equipment.This topic combines it with capillary electrophoresis technology to realize the capillary electrophoresis amperometric detection circuit that integrates the generation,conversion,amplification,acquisition and graphical display of electrochemical signals,which can realize the portable measurement of ion concentration in polluted water.This subject is based on a three-electrode system,using differential pulse anodic stripping voltammetry as the detection method,and designing the ampere detection circuit software and hardware,upper computer and de-noising algorithm to realize the detection function of heavy metal ions.With STM32F103ZET6 as the core,it uses its built-in DAC external offset circuit and constant potential circuit to achieve differential pulse voltage output.The waveform of the scan pulse voltage is controlled by the program,and the corresponding differential pulse is added to the three-electrode system.The anode discharge current is converted into voltage value through microcurrent amplification module and ADC acquisition circuit,which is filtered and amplified to be collected through AD7172-2.After A/D conversion,the data is transmitted back to MCU through SPI,and then the processed data is transmitted to the upper computer designed by Lab VIEW through USB serial port.The upper computer processes the received data through the transfer of six states,generates the stripping volt-ampere curves and stores the experimental data.Finally,the de-noising algorithm of the improved threshold function combining the dual tree complex wavelet transform and translation invariant is used for the de-noising of the stripping voltammetry curve.The de-noising stripping voltammetry curve is quantitatively and qualitatively analyzed,and the standard curve is obtained with standard solution,and then the sample solution is tested.The experiment measured that the ampere detection circuit has good performance,the detection of Pb²⁺and Cd²⁺adopts the method of synchronous bismuth coating,and its concentration has good linearity and repeatability in the range of 100-1000ppb.The detection limits of Pb²⁺and Cd²⁺are 63.5ppb and 83.1ppb,respectively.Compared with the electrochemical workstation,the relative deviation is about 3%.The ampere detection circuit designed in this subject has good accuracy and can detect a variety of heavy metal ions.It is portable and convenient for practical use.