Title:  Micromagnetic Intracochlear Stimulation: Microcoil Array Modeling, Fabrication, and Validation

Committee: 

Dr. Bhatti, Advisor        

Dr. Scott, Chair

Dr. Inan

Abstract: The objective of the proposed research is to develop, characterize, and demonstrate functional microcoil arrays for micromagnetic stimulation of neural elements, designed to improve the spatial resolution of cochlear implants. Commercialized cochlear implants operate using direct current injection. As the cochlea is filled with a conductive bodily fluid, the injected current causes a spread of excitation and impacts user hearing quality. Magnetic stimulation serves as a potential solution to the spread of excitation as magnetic fields are impervious to the material properties of the biological environment. Magnetic stimulation of coil arrays demonstrate improved spatial resolution of stimulation sites. In this work, I will investigate the performance of a newly designed planar microcoil array with finite-element modeling (FEM) software. The microcoil will be integrated onto a biocompatible, non-planar multicoil array that may be safely implanted. The developed microcoils will be tested in vitro by observing the eddy currents projected onto a phantom gel. These microcoils provide a potential solution for neural stimulation that may be easily integrated onto the existing commercialized implant structure. Currently, the microcoils exhibit electromagnetic behaviors with the potential to stimulate neurons in the inner ear. With a target diameter of 600 um, scaled prototype coils (100x) were inkjet fabricated and tested to corroborate FEM studies. The activating function of the planar coil geometry was observed to characterize neural stimulation capabilities. To achieve batch-reproducable coils sized for cochlear implantation, miniaturization was performed using aerosol jet printing (AJP).