Frequency Selectivity of an Artificial Cochlear Sensory Epithelium in a Liquid based on Electrical Voltage Output

Abstract

Advancing medical applications, artificial auditory epithelia which emulate cochlear sound reception have been developed by microelectromechanical systems technologies. Successfully fabricating an arched trapezoidal piezoelectric thin-film device designed for cochlea's 3D spiral structure, we confirmed resonance characteristics using laser Doppler vibrometer. However, lead-free organic piezoelectric thin films for future animal tests have the length in the longitudinal direction of 3 mm, hindering precise voltage output measurement. Consequently, verifying frequency selectivity remains incomplete. To address this bottleneck, we optimized performance through reevaluated annealing conditions by analyzing the crystal structure of the piezoelectric film using X-ray diffraction. Assessing frequency selectivity through voltage output in silicone oil, replicating endolymph fluid properties, we found distinct resonance frequencies of 100 kHz and 130 kHz at different positions, showing cochlear implant potential for natural-like frequency selectivity.