An Ultra Compact Integrated Front End for Wireless Neural Recording Microsystems

The design and performance of an integrated front end for high-channel-count neural recording microsystems is presented. This front end consists of a 3-D micromachined microelectrode array, realized using a new architecture that allows simple and rapid microassembly. A 64-site 3-D multiprobe, realized using the new architecture, interfaces with tissue volumes of less than 0.01 mm(3) and has a footprint of 1 mm(2). For amplification, filtering, and buffering of the recorded neural signals, a custom signal-conditioning circuit provides high gain (60 dB), low noise (4.8 mu V-rms), and low power (50 mu W) in an area of 0.098 mm(2). In addition, this circuitry implements bandwidth tuning, offset compensation, and wireless gain programmability. This new approach to system integration uses a microfabricated parylene overlay cable to electrically interconnect the 3-D array and signal-conditioning circuitry. In vivo results obtained using this integrated microsystem front end in its most compact form are presented.