Towards a Microfabricated Flexible Graphene-Based Active Implant for Tissue Monitoring During Optogenetic Spinal Cord Stimulation
Andrada Iulia Velea (TU Delft - Bio-Electronics)
S. Vollebregt (TU Delft - Electronic Components, Technology and Materials)
T.B. Hosman (Fraunhofer Institute for Reliability and Microintegration IZM, TU Delft - Bio-Electronics)
A. Pak (TU Delft - Bio-Electronics, Fraunhofer Institute for Reliability and Microintegration IZM)
Vasiliki Giagka (TU Delft - Bio-Electronics, Fraunhofer Institute for Reliability and Microintegration IZM)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
This work aims to develop a smart neural interface with transparent electrodes to allow for electrical monitoring of the site of interest during optogenetic stimulation of the spinal cord. In this paper, a microfabrication process for the wafer-level development of such a compact, active, transparent and flexible implant is presented. Graphene has been employed to form the transparent array of electrodes and tracks, on top of which chips have been bonded using flip-chip bonding techniques. To provide high flexibility, soft encapsulation, using polydimethylsiloxane (PDMS) has been used. Making use of the "Flex-to-Rigid" (F2R) technique, cm-size graphene-on-PDMS structures have been suspended and characterized using Raman spectroscopy to qualitatively evaluate the graphene layer, together with 2-point measurements to ensure the conductivity of the structure. In parallel, flip-chip bonding processes of chips on graphene structures were employed and the 2-point electrical measurement results have shown resistance values in the range of kΩ for the combined tracks and ball-bonds.