Design of the UCH/RNID cochlear implant system

This paper describes the design of the UCH/RNID single channel, extracochlear, auditory prosthesis. The system employs a body-worn analogue sound processor whose output is transmitted to a pair of implanted Platinum/Iridium stimulating electrodes via a transcutaneous inductively coupled link. The stimulating current is passed between a 1 mm diameter ball electrode, resting in the round window, and a 5 mm square foil electrode placed under the temporalis muscle. The implanted amplitude modulation receiver circuit is fabricated from hermetically sealed electronic components which are mounted on a ceramic substrate. The implanted circuit is encapsulated in silicone rubber. The primary design objective was to produce a reliable and effective auditory prosthesis costing less than 1,000 pounds.