Computing Cochlear Implant Electrode Interface Impedance based on Electric Field Imaging

Electric field imaging (EFI) is a valuable approach in cochlear implant (CI) research, which is used to study the potential distribution inside the cochlea and examine whether the implanted electrodes are functioning properly. Accurate knowledge of the electrode interface impedance is critical for improving CI performance. A 3D patient-specific CI model was built to simulate EFI using the finite element method (FEM). Intracochlear potentials were recorded by multiple sensing electrodes and the corresponding impedance values were computed. The simulation results were compared with the EFI data obtained from the clinical measurements. The EFI simulated by patient-specific and generic electrode trajectories were also compared. Results showed that the patient-specific trajectory simulations were consistent with the clinical measurements. The impedance value computed in this research has the potential to increase the accuracy of evoked compound action potential (ECAP) simulations.