Study on the Influence of the Surface Contact Impedance of Microelectrodes

Microfluidics chips are widely used in cell detection of electrochemical impedance spectroscopy. As the core component of microfluidics chips, the surface characteristics of microelectrodes affect the accuracy detection. Due to the existence of electrostatic effect, ions and dipoles with opposite charges in the solution are adsorbed on the electrode surface, thus forming an electrical double layer (EDL) structure on the microelectrode surface, which seriously affects the accuracy. In this study, the parameter $k_{zc}$ is proposed to illustrate the influence of contact impedance under microelectrode conditions, and mathematical models is constructed for each structure of EDL. Subsequently, contact impedance experiments were conducted with pure water and NaC1 solution as the medium. The experimental results show that the theory proposed in this paper can better explain the impact of microelectrode contact impedance on EIS (electrochemical impedance spectroscopy, EIS) experience in Microfluidics chips.