Study of microelectronics for detecting and stimulating of central neural signals

Test circuits for the signal detection and the function electrical stimulation (FES) of neurons have been designed, implemented at first by using discrete devices and characterized off-body. The detecting circuit consisting of three-stage operational amplifiers has a controllable gain up to 10/sup 5/, a -3 dB bandwidth of 30 kHz, and an equivalent input noise of about 9 nV//spl radic/Hz. The FES circuit consisting of two-stage operational amplifiers has a bandwidth of more than 10 kHz and a variable gain from 20 dB to 60 dB can provide a current of more than 1 mA to a load of 10 k/spl Omega/ They are intended to connect with both cuff-type and staff-type microelectrodes. Integrated circuits (IC) for the neural signal process have been designed with features of low voltage and low power. A more biocompatible composite has been synthesized to modify the silicon and related material.