Fabrication of a flexible three-dimensional neural microelectrode array

A fabricating method for the flexible 3D protruding Microelectrode Arrays(MEAs) for neural applications was proposed.This method used a photosensitive polyimide(Durimide 7510) as substrate and an anisotropically etched Si as mold to fabricate a flexible pyramid-shaped microelectrode array by combining a micro-molding technique,a metallic patterning and an electrochemical-based sacrificial layer technique.An evaluation for 3D protruding electrode was also performed by simulation,SEM and resistance test,and the 3D flexible polyimid-based microelectrode with 4 × 4 array of electrode sites was fabricated using the proposed method,in which each individual electrode site has base area of 60 μm×60 μm and the height of 37 μm in pyramid shaped tip.Compared with conventional planar microelectrodes in the same base area,the electrode impedance of 3D pyramid-shaped microelectrode decreases by 63%.The results show that the pyramid-shaped electrode configuration allows electrode sites to be close to target neurons.On the other hand,the pyramid-shaped configuration can reduce electrode impedance and increase charge injection,which is helpful to neural stimulation.