CMOS-Based High-Density Silicon Microprobe Arrays for Electronic Depth Control in Intracortical Neural Recording–Characterization and Application

This paper reports on the characterization and intracortical recording performance of high-density complementary-metal–oxide–semiconductor (CMOS)-based silicon microprobe arrays. They comprise multiplexing units integrated on the probe shafts being part of the signal transmission path. Their electrical characterization reveals a negligible contribution on the electrode impedances of $139 \pm 11\ \hbox{k}\Omega$ and $1.2 \pm 0.1\ \hbox{M}\Omega$ and on the crosstalks of 0.12% and 0.98% for iridium oxide $( \hbox{IrO}_{x})$ and platinum (Pt) electrodes, respectively. The power consumption of the single-shaft probe was found to be 57.5 $\mu\hbox{W}$ during electrode selection. The noise voltage of the switches was determined to be 5.6 $ \hbox{nV}/\surd\hbox{Hz}$; it does not measurably affect the probe performance. The recording selectivity of the electrode array is demonstrated by electrical potential measurements in saline solution while injecting a stimulating current using an external probe. In-vivo recordings in anesthetized rats using all 188 electrodes with a pitch of 40.7 $ \mu\hbox{m}$ are presented and analyzed in terms of single neural activity and signal-to-noise ratio. The concept of electronic depth control is proven by performing mechanical translation of the probe shaft while electronically switching to adjacent electrodes to compensate the mechanical shift. $\hfill$[2012-0027]