Acousto-sensitive ion-based transistors and soft electronics for artificial basilar membrane
Linta Sohail a, George Spyropoulos a
a Department of Information Technology, Faculty of Engineering and Architecture, Ghent University, Technologiepark Zwijnaarde 126, 9052 Zwijnaarde, Belgium
Proceedings of Bioelectronic Interfaces: Materials, Devices and Applications (CyBioEl)
Limassol, Cyprus, 2024 October 22nd - 25th
Organizers: Eleni Stavrinidou and Achilleas Savva
Oral, Linta Sohail, presentation 060
Publication date: 28th June 2024

Current solutions for hearing impairment lie vastly in cochlear implants (CIs). However, they are limited by bulky, power-demanding external discomfortable components that hinder sound localization and suboptimal neural interfaces which negatively impact the efficiency of hearing restoration. To overcome these issues, I aim to exploit novel internal ion-gated electrochemical transistors (IGTs) and piezoelectric (PVDF) nanofibers to establish a soft, biocompatible artificial basilar membrane (ABM) for a fully implantable and self-contained CI. We hypothesize that organic electronics can create all the required components; IGT-based acousto-electrical transducers with a high signal-to-noise ratio (SNR), and low-impedance, stable stimulation electrodes. This will lead to a membrane with 8 intracochlear excitation points that conforms to the intact basilar membrane, generates, and amplifies electrical pulses (>x103 ) according to incoming acoustic stimuli, to stimulate the spiral ganglion neurons and restore hearing without external components. To achieve that, we create efficient and fast acousto-sensitive IGTs (gm/τ > 106 mSs-1), high capacitance conductive polymer films, overcome stability issues and design smart fabrication routes that allow the development of all components into a single conformable substrate. We achieve that by tuning materials composition, improving designs, and better understanding the geometry and morphology effects on piezoelectric nanofibers. We explore IGT-arrays gated by continuous electrospun PVDF nanofiber (~0.6µm fiber dia) films with gradually decreasing areas, to provide a deeper understanding of the device physics and elucidate their exact operating principle under various acoustic stimulations (0.1-10kHz). We also investigate the effect of the of acousto-sensitive IGT arrays on cell viability (>70%)  and their electrical interface with tissue (8kΩ @ 1kHz) in-vitro. We examine their performance in-vivo by recording the electrically evoked auditory brain recordings (ABRs)  in a rat model.

 

This project will generate safer, smaller, and more conformable acoustic-sensitive devices and stimulation electrodes that will build an ABM that can modulate the electrically neurophysiological activity of the spiral ganglion neurons. Further, the materials and methods that will be used in this project will lay the foundation for cost-effective and improved neurological devices such as micro-EEG systems and brain stem implants.

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