Fabrication and evaluation of a silicon probe array on a flexible substrate for neural recording

Microelectrodes for neural recording fabricated by MEMS technologies have many advantages of the size, the number of the channels, and so on. However, conventional microelectrode for neural recording was fabricated on the solid substrates. They have the possibility to damage the target tissues when the animals are in motion. And it is difficult to attach and fix them to the target tissues. In order to solve these problems and to realize long-term stable multichannel recording, a micro probe array based on a flexible polyimide substrate was designed and fabricated. Etching a silicon wafer using Deep RIE equipment formed each probe. This type of flexible microelectrode can be attached around the soft neural tissue, and change its shape when the target transforms. During the fabrication using DRIE, we succeeded to integrate interconnecting wires with the microprobes. To get enough strength to insert into the tissues, parylene was coated on the microelectrode. In this paper, we have investigated the fabrication process and the flexibility of the electrode to estimate the utility for the application to tissues.