Book/Dissertation / PhD Thesis

FZJ-2021-02401

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Development, characterization, and application of compliant intracortical implants

Srikantharajah, K. (Corresponding author)FZJ*

2021
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-587-1

Please use a persistent id in citations: http://hdl.handle.net/2128/29363  urn:nbn:de:0001-2021122122

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

Note: Dissertation, RWTH Aachen University, 2021

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Contributing Institute(s):

1. Bioelektronik (IBI-3)

Research Program(s):

1. 523 - Neuromorphic Computing and Network Dynamics (POF4-523) (POF4-523)

Appears in the scientific report 2021

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