Biocompatible and plastic neural interface devices allow
for minimally
invasive recording of brain activity. Increasing electrode density
in such devices is essential for high-resolution neural recordings.
Superimposing conductive leads in devices can help multiply the number
of recording sites while keeping probes width small and suitable for
implantation. However, because of leads’ vertical proximity,
this can create capacitive coupling (CC) between overlapping channels,
which leads to crosstalk. Here, we present a thorough investigation
of CC phenomenon in multi-gold layer thin-film multi-electrode arrays
with a parylene C (PaC) insulation layer between superimposed leads.
We also propose a guideline on the design, fabrication, and characterization
of such type of neural interface devices for high spatial resolution
recording. Our results demonstrate that the capacitance created through
CC between superimposed tracks decreases non-linearly and then linearly
with the increase of insulation thickness. We identify an optimal
PaC insulation thickness that leads to a drastic reduction of CC between
superimposed gold channels while not significantly increasing the
overall device thickness. Finally, we show that double gold layer
electrocorticography probes with the optimal insulation thickness
exhibit similar performancesin vivowhen compared
to single-layer devices. This confirms that these probes are adequate
for high-quality neural recordings.