Design And Fabrication Of Three Electrode Structure For Amperometric Detection Of Microfluidic Chip

With the development of microfluidic technology,its detection technology has been a research hotspot.In line with the requirements of portability,high integration and easy operation,electrochemical detection has been widely used,among which amperometric detection has attracted much attention due to its own advantages.Because the amperometric detection electrode and other functional units in the microfluidic chip are prepared on the same substrate,it is more difficult to replace the electrode when it is polluted,and it is necessary to increase a certain area to prepare the electrode when it is unable to replace the electrode.Therefore,it is limited to a certain extent.In view of the above problems,the preparation technology of three electrode system for amperometric detection was studied,and the prepared electrode was used for heavy metal detection.Firstly,the electrochemical principles such as electrode reaction dynamics are analyzed,and the influencing factors such as the setting of boundary conditions are familiar with.A three-dimensional diffusion model of the working electrode is established and simulated.The simulation results show that the area of the electrode does not affect the current density.However,the geometry has a certain influence on the current density,and the circular structure is better than the rectangular structure.The distance between electrodes has a certain influence on the current,and the current decreases with the increase of the distance.Secondly,the structure of the three electrodes is designed by combining with the simulation idea.The working electrodes are circular and rectangular,and the electrode spacing is 0.7mm and 1mm.The PCB board is selected as the base material of the amperometric detection electrode,and the three electrode structure is fabricated on it by using the PCB processing technology.The results of cyclic voltammetry show that the mass transfer mode of surfactant is diffusion mode;The performance of three electrode system with circular working electrode is better than that of three electrode system with rectangular working electrode;Under the same conditions,the smaller the distance,the better the performance of the three electrodes.Therefore,the circular three electrode with electrode spacing of 0.7mm has the best performance.In order to improve the sensitivity of the electrode,sandblasting method and spin coating method were used to modify the working electrode.When sandblasting,the pressure and sandblasting times were combined to modify the micro structure of the electrode.The results show that the higher the pressure is,the higher the frequency of sandblasting is.The results show that with the increase of concentration,the sensitivity of the electrode is better.Comparing the sensitivity of planar structure electrode,micro structure electrode and nano structure electrode,the sensitivity of nano structure electrode is higher.The results show that the detection efficiency of nanostructure is 20 times higher than that of planar electrode and 10 times higher than that of micron electrode.And the detection of nanostructure is 1ppb,so its sensitivity is the best.