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.
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[2012-0027]