Abstract
This research is to design a “Micro Multi-Probe Electrode Arrays for Neural Signal Recording System”. The final goal is to apply the measurement system on bio-medical applications. Based on the optimal design of micro multi-probe electrodes by Ansys, the fabrication of electrodes can be accomplished by using MEMS technology. At the end, the performance of electrodes would be measured, which will be very useful for further development of measurement system. Brain is a complicated system that sends electrical signal by thousand hundred million neurons. The process of signal is a very complicated network. As a result of the micro probe electrode would be used to measure neural signal of brain cortex, the intensity of electrode is very critical. Several kinds of geometry were applied to simulate by ANSYS before designing fabrication process. The shank geometry 1/4 Cycle (Pillar) is the proper one that can bear 18.5mN force. MEMS technology was used to develop the fabrication of micro multi-probe electrodes, which started by using SOI wafer. Lithography, LPCVD, dry etching, PVD, etc were used to develop the micro electrodes on the SOI wafer. The yield of designed fabrication can reach 98%. The feature of process inherently can control the final probe thickness based on the thickness of device layer of the SOI wafer. Then we used the electrochemical alternative current impedance analysis to measure the impedance and phase between electrode and electrolyte, and then to obtain the capacitance of electrode double layer. It is beneficial for us to set up the circuit of the further jobs in the future. To avoid the loading effect, it is useful to allocate the suitable matching resistance, which could be used to decrease the noise of OPamp and decide the proper cut frequency of high pass filter in order to to obtain the original neural signals. Future work is to use current accomplished results to for developing a completed measurement circuitry. To reduce noise of the neural signal is very important. The final goal is to implant multi-channels by using developed electrode array and to inject medicine for some medical treatments.