Acousto-Sensitive Ion-Based Transistors and Soft Electronics for Artificial Basilar Membrane

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, we 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 hypothesized 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. To achieve that, we created efficient and fast acousto-sensitive IGTs (<i>gm</i>/τ &gt; 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 tuned materials composition, improved designs, and investigated the geometry and morphology effects on piezoelectric nanofibers. We explored IGT-arrays gated by continuous electrospun PVDF nanofiber (~0.6µm diameter fiber) 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).. This work lead to an ABM with 8 intracochlear excitation points that conforms to the intact basilar membrane, generates, and amplifies electrical pulses (&gt;x10³) according to incoming acoustic stimuli, to stimulate the spiral ganglion neurons and restore hearing without external components. We examined the performance of the ABM in-vivo by recording the electrically evoked auditory brain recordings (ABRs) in a rat model.<br/><br/>This project will generate safer, smaller, and more conformable acoustic-sensitive devices and stimulation electrodes that will build an ABM that can modulate electrically the 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.