Intelligent system for impedance stabilization of model cochlear implantable electrodes

Abstract

This thesis aimed to develop a neurostimulator for testing various stimulation strategies to stabi-lize electrode impedance in medical devices like cochlear implants. These devices have restored hearing to individuals with profound deafness. However, their performance is often hindered when the immune response leads to the formation of fibrous tissue around the electrodes, which increases impedance and can impair their function. Previous research suggests that early stages of the immune response can be modulated through electrical stimulation, but testing this hypothesis is difficult due to the need for multiple stimulation pulses, making it impractical. The challenge is compounded by the lack of stimula-tors that automatically switch between signals. This study focused on developing an electrostimulator that can autonomously alternate between signals without manual intervention, enabling faster test-ing of different strategies. Electrodes designed for cell culture were used to evaluate the stimulator’s performance. Fibroblast cells were cultured on these model electrodes to simulate the tissue response in vitro, mimicking the conditions of cochlear implant electrodes. The simulator was programmed to deliver 24 different signals over 12 hours, with each signal applied for 1 minute, followed by 30 min-utes of no stimulation. This automated sequence eliminates manual intervention, allowing for a more efficient process. The main outcome of this research was the development of a neurostimulator that can test several parameters for controlling tissue responses. In this case, the stabilization of electrode impedance, which can be affected by cellular interactions that lead to the formation of fibrotic tissue. Indeed, the capabilities of this technology extend beyond impedance stabilization. For instance, to test stimulation strategies to control neuronal behavior.