Development and Characterization of a Biomimetic Totally Implantable Artificial Basilar Membrane System

Cochlear implants (CIs) have become the standard treatment for severe-to-profound sensorineural hearing loss. Conventional CIs have some challenges, such as the use of extracorporeal devices, and high power consumption for frequency analysis. To overcome these, artificial basilar membranes (ABMs) made of piezoelectric materials have been studied. This study aimed to verify the conceptual idea of a totally implantable ABM system. A prototype of the totally implantable system composed of the ABM developed in previous research, an electronic module (EM) for the amplification of electrical output from the ABM, and electrode was developed. We investigated the feasibility of the ABM system and obtained meaningful auditory brainstem responses of deafened guinea pigs by implanting the electrode of the ABM system. Also, an optimal method of coupling the ABM system to the human ossicle for transducing sound waves into electrical signals using the middle ear vibration was studied and the electrical signal output according to the sound stimuli was measured successfully. Although the overall power output from the ABM system is still less than the conventional CIs and further improvements to the ABM system are needed, we found a possibility of the developed ABM system as a totally implantable CIs in the future.

Fabrication of Si3N4-Based Artificial Basilar Membrane with ZnO Nanopillar Using MEMS Process

This paper presents the fabrication of Si3N4-based artificial basilar membrane (ABM) with ZnO nanopillar array. Structure of ABMs is composed of the logarithmically varying membrane fabricated by MEMS process and piezonanopillar array grown on the Si3N4-based membrane by hydrothermal method. We fabricate the bottom substrate containing Si3N4-based membrane for inducing the resonant motions from the sound wave and the top substrates of electrodes for acquiring electric signals. In addition, the bonding process of the top and bottom substrate is performed to build ABM device. Depending on sound wave input of the specific frequency, specific location of the ABM produces a resonant behavior. Then a local deformation of the piezonanopillar array produces an electric signal between top and bottom electrode. As experimental results of the fabricated ABM, the measured resonant frequencies are 2.34 kHz, 3.97 kHz, and 8.80 kHz and the produced electrical voltages on each resonant frequency are 794 nV, 398 nV, and 89 nV. Thus, this fabricated ABM device shows the possibility of being a biomimetic acoustic device.