Fully Immersible Subcortical Neural Probes With Modular Architecture and a Delta-Sigma ADC Integrated Under Each Electrode for Parallel Readout of 144 Recording Sites

This paper presents a needle-shaped neural probe which integrates an incremental
$\Delta \Sigma $
-ADC under each electrode in an area of
$70\times 70\,\,\mu \text{m}^{\mathrm{ 2}}$
. The modular architecture avoids global routing of noise sensitive neural signals and connects with a digital four-wire interface. The re-configurable 5.6/11.5 mm needle enables parallel readout of all 64/144 integrated recording sites and features a constant width and thickness of
$70\times 50\,\,\mu \text{m}^{\mathrm{ 2}}$
from top to bottom allowing to be fully implanted for deep brain monitoring applications. Platinum or iridium-oxide electrodes can be deposited in a custom post-CMOS process. The functionality of the recording system is demonstrated in an
in vivo
setup. The noise performance of 6.02
$\mu \text{V}_{\text {rms}}$
for LFP signals (1–300 Hz) and 10.46
$\mu \text{V}_{\text {rms}}$
for AP signals (300 Hz–10 kHz) is obtained at a power consumption of 39.14
$\mu \text{W}$
per recording site.