Multi-channel micro neural probe fabricated with SOI

Silicon-on-insulator (SOI) substrate is widely used in micro-electro-mechanical systems (MEMS). With the buried oxide layer of SOI acting as an etching stop, silicon based micro neural probe can be fabricated with improved uniformity and manufacturability. A seven-record-site neural probe was formed by inductive-coupled plasma (ICP) dry etching of an SOI substrate. The thickness of the probe is 15 μm. The shaft of the probe has dimensions of 3 mm×100 μm×15 μm with typical area of the record site of 78.5 μm². The impedance of the record site was measured in-vitro. The typical impedance characteristics of the record sites are around 2 MΩ at 1 kHz. The performance of the neural probe in-vivo was tested on anesthetic rat. The recorded neural spike was typically around 140 μV. Spike from individual site could exceed 700 μV. The average signal noise ratio was 7 or more. Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2005CB724302), the National High-Tech Research and Development Program of China (“863” Project) (Grant Nos. 2007AA04Z329, 2007AA03Z427) and the National Natural Science Foundation of China (Grant No. 60776024)