Improvement of Electrical Properties of Si-Microprobe Electrode Arrays for Neural Recording

摘要

This paper reports on realization of Si-microprobe array and improvement of electrical properties of the probe array as multi-electrode neural recording sensor. Si microprobe can be formed on Si(111) substrate by Vapor-Liquid-Solid (VLS) crystal growth using Au as catalyst and Si{sub}2H{sub}6 as gas source of Si. VLS method uses low temperature of about 600°C and hence it is compatible with IC process, such as making amplifiers or impedance converters. Thus, Si microprobe can become very useful sensing device to measure neural signals which has very small voltage change of tens μV order. Si microprobe is also minimally-invasive for penetrating tissue because the probe has very small diameter and narrow tip. The tip of Si probe should be covered biocompatible metal film to keep living and make it a snap to measure electrical signal in tissue fluid. So the metal film dictates electrical property of the Si probe as biomedical electrode. In bioinstrumentation field, Au is commonly used as metal electrode; however, it is known that Pt or Ir can be finer than Au as biomedical electrode. Therefore, we report applying Pt and Ir to Si probe.