Research On Extracellular Recordings From Microelectrode Array

A new method of measuring action potentials called extracellular recordings from microelectrode array involves cell culture and real-time signal detection. The recording technique is multi-channel, non-invasive, fast-response, simple-fabrication and long-term, so it has been applied in biomedical science, high-throughput drug screening and other fields. But it’s hard to solve the problem that the signal-to-noise is a little low due to lack of a complete equivalent circuit of electrophysiological detection and a quantitative analysis tool. Besides, commercial detecting equipment has a high price and low flexibility.In view of the above problems, the production mechanism and dynamic process of electrophysiological signal is first described by theoretical analysis and formula deduction. Next, the complete equivalent circuit of the junction between cell and microelectrode is constructed by a circuit simulation program called Multisim to quantitatively analyze the whole electrochemical process. Then, of microelectrode-electrolyte interface impedance and microelectrode array thermal noise, two complete expressions are deduced, which is important to extracellular recordings. Meanwhile, theoretical AC impendence spectroscopy is derived on basis of these expressions. After that, the equivalent circuit is simulated by inputting different values of some physical quantities in order to know how much they have influence on electrophysiological signal, which decides the concrete design scheme of microelectrode parameters. At last, a detecting system is designed and constructed with low cost and high flexibility. It is proved to meet the needs of electrophysiological detection by simulation and real test.