International Symposium on LifeChips 2006

Bringing Hearing to the Deaf: Challenges for MEMS
Deafness is a tragically debilitating condition for millions of people worldwide. Severe and profound deafness can be helped with artificial ears: cochlear implants. More than 60,000 people have received implants throughout the world. Cochlear prostheses have been enhanced since their introduction in the late 1970s. Still, there is room for dramatic improvement if some engineering challenges are met. Another source of deafness, presbycusis or old-age hearing loss, affects more than 25 million people in the US. One form of presbycusis, strial presbycusis affects about eight million people and may be overcome by the application of DC currents to specific regions of the inner ear. MEMS was proposed for cochlear implants nearly 30 years ago. Integrated circuits make cochlear prostheses possible, but microfabrication could be used to much greater advantage. Some ideas will be presented, with physiological results that suggest that they might be helpful for implants of the future. Some techniques are in production, while others are in their infancy. All provide exciting possibilities for therapy and wonderful challenges for engineers. Strial presbycusis presents the challenge of the generation of DC currents with metallic electrodes. One approach is similar to the chopper technology that was used in electronics to make power supplies and DC amplifiers decades ago. That approach requires a small, reliable MEMS valve that can be produced in large quantity and that can work consistently over millions of cycles. Specifications for such a valve will be presented to spur discussion. Even with such a valve in existence, it will be necessary to ensure that the inner ear can tolerate the imposition of DC currents for long durations. Physiological results will be presented, and will be used to raise questions about the engineering design of prosthesis that can be used for several decades in human patients.

Biography
Francis A. (Sandy) Spelman earned his BSEE from Stanford University in 1959, his MSEE from the University of Washington in 1968, and his doctorate from the University of Washington in 1975. He worked as a research engineer at the Regional Primate Research Center at the University of Washington from 1961-2001, and became a member of the faculties of Bioengineering, Electrical Engineering and Otolaryngology/Head and Neck Surgery in 1977. He retired from the UW in 2001 after serving as a professor and as Acting Chair of the Department of Bioengineering. He is currently a Senior Researcher at Advanced Cochlear Systems of Snoqualmie, WA, where he works on artificial ears for the deaf and on old-age hearing loss. Sandy is a Fellow of the Institute of Electrical and Electronics Engineers, from which he was awarded a Third Millennial Medal in 2000, an Inaugural Fellow of the Biomedical Engineering Society, and a Member of the Association for Research in Otolaryngology.