VLSI potentiostat array for distributed electrochemical neural recording

A neurochemical sensor system is being developed to spatially sense and process neurotransmitters. This paper reports the design and VLSI implementation of a multichannel potentiostat that interfaces to a nitric-oxide (NO) sensor array. Picoampere to microampere input currents are range-normalized with programmable gain, and digitized by a bank of current-mode delta-sigma analog-to-digital (A/D) converters. First-order noise shaping and 4096-fold oversampling provide high signal-to-noise ratio for the low-frequency NO transients. A shift register scans the buffered decimated delta-sigma outputs in bit-serial format providing asynchronous sequential readout. An 8-channel potentiostat in 0.5 /spl mu/m CMOS measures 1.5 mm/spl times/1.5 mm, and consumes 0.5 mW power. The device is expected to serve as a valuable tool for neurophysiological research and implantable neural prostheses.

一种神经化学传感器系统正在被开发，用于对神经递质进行空间感知和处理。本文报道了一种与一氧化氮（NO）传感器阵列接口的多通道恒电位仪的设计及超大规模集成电路（VLSI）实现。皮安到微安级的输入电流通过可编程增益进行量程归一化，并由一组电流模式的Δ - Σ模数转换器（A/D）进行数字化。一阶噪声整形和4096倍过采样为低频NO瞬变提供了高信噪比。一个移位寄存器以位串行格式扫描缓冲后的抽取Δ - Σ输出，提供异步顺序读出。一个采用0.5μm互补金属氧化物半导体（CMOS）工艺的8通道恒电位仪尺寸为1.5mm×1.5mm，功耗为0.5mW。该器件有望成为神经生理学研究和植入式神经假体的一种有价值的工具。