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@PHDTHESIS{Srikantharajah:892862,
author = {Srikantharajah, Kagithiri},
title = {{D}evelopment, characterization, and application of
compliant intracortical implants},
volume = {73},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2021-02401},
isbn = {978-3-95806-587-1},
series = {Schriften des Forschungszentrums Jülich. Reihe Information
/ Information},
pages = {xiv, 155, xv-xvii S.},
year = {2021},
note = {Dissertation, RWTH Aachen University, 2021},
abstract = {Over more than half a century, neural interfaces enabled
various breakthroughs to treat patients suffering from
neurodegenerative diseases. Up to now, only a few neural
devices were able to demonstrate significant clinical
impact, such as deep brain stimulation and cochlear
implants. However, these probes are exclusively used for
stimulating neural activity. As long-term monitoring of, or
even bi-directional communication with, the brain still
remains challenging, much effort has been devoted in the
last years to optimize probe dimensions and to implement low
Young’s modulus polymers as substrate materials for the
device fabrication. With the goal to produce
next-generation, compliant, intracortical probes suitable
for chronic implantation, a Michigan-style array was
designed by minimizing the probe dimensions and reducing the
mismatch between the device and tissue. To this end, an
array consisting of four shanks with cross-sections per
electrode of 250 $\mu$m$^{2}$ were produced using ParyleneC,
a biocompatible and soft polymer, as substrate material.
Furthermore, to obtain high quality recordings, a low
impedance coating was established utilizing spin-coated
PEDOT:PSS. The recording sites with a geometric surface area
of 113 $\mu$m$^{2}$ were covered with 610nm thick PEDOT:PSS,
resulting in an impedance of 2.650 M$\Omega$·$\mu$m$^{2}$.
As compliant probes need to be mechanically reinforced
during implantation, a tissue-friendly insertion system was
developed to reduce the effective length of the
intracortical probes by introducing a temporary polyethylene
glycol coating. The soft and flexible shanks, with a length
of 2 mm, were successfully implanted into the mouse barrel
cortex without inserting the bulky coating, which minimized
the acute trauma during insertion. The compliant implants
were able to simultaneously detect local field potentials as
well as single-unit and multi-unit activities with a maximum
SNR of 7. Additionally, more quality units (SNR>4) were
isolated from the recordings using compliant devices in
contrast to commercially available traditional stiff probes.
These promising outcomes lay the groundwork for future
long-term stability validations of compliant intracortical
implants and is one step closer towards designing
chronically stable devices with seamless biointegrationu},
cin = {IBI-3},
cid = {I:(DE-Juel1)IBI-3-20200312},
pnm = {523 - Neuromorphic Computing and Network Dynamics
(POF4-523)},
pid = {G:(DE-HGF)POF4-523},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
urn = {urn:nbn:de:0001-2021122122},
url = {https://juser.fz-juelich.de/record/892862},
}