Measurement of forces at the tip of a cochlear implant during insertion

An optical fiber-based sensor has been developed to measure the forces at the tip of an electrode array during insertion into the cochlea. The sensor, utilizing optical fiber Bragg grating technology, was incorporated into a custom-designed Pt-banded electrode array for guinea pigs. In vivo experiments were undertaken in which forces at the tip of the array were measured in real time during the insertion. Data were obtained for maximum insertion forces of up to 254 mN. Histology was performed on the excised cochleae with the sensors fixed in position to evaluate the level of insertion trauma. The insertion experiments demonstrated a clear correlation between the applied force and collateral tissue damage.