Part 2–A 32-Site 4-Channel Cochlear Electrode Array

Pamela Bhatti, Graduate Student, Univ. of Michigan
ABSTRACT: (Pamela Bhatti) Using 16-22 wire electrodes, a cochlear prosthesis bypasses failed hair cells of the inner ear to electrically stimulate the auditory nerve restoring functional hearing in over 90,000 cochlear implant recipients. Such implants have been remarkably effective, but considerable differences in sound perception remain among patients. A potential solution is to develop electrode arrays with significantly increased numbers of stimulating sites that better exploit the cochlea’s acoustic frequency-to-place mapping. Since increasing the number of wire electrodes is precluded by the size of the cochlea for contemporary wire bundle based electrode arrays, we present a promising alternative—a high-density thin-film cochlear electrode array. Developed to improve both pitch perception and reduce insertion damage, the silicon-parylene substrate supports 32 iridium-oxide sites on 250 µm centers, along with circuitry for current generation and position sensing. Interfacing over eight leads at ±3V, stimulus pulses cover ±500 µA on four parallel channels with 8-bit resolution and a minimum pulse width of 4 µs.

BIO: Pamela T. Bhatti received a B.S. in Biomedical Engineering from the University of California, Berkeley in 1989, and an M.S.E.E. from the University of Washington, Seattle, in 1993. She expects to complete her Ph.D. in Electrical Engineering from the University of Michigan, Ann Arbor in July 2006. From 1987-1990, she was a member of the technical staff at Alza Corporation where she conducted clinical and experimental processing of controlled release drug delivery systems. From 1994 to 1995, she was with Motorola's Semiconductor Products Sector, where she developed and participated in an engineering rotation program for the MOS Digital and Analog Integrated Circuits Division, and later as an Applications Engineer with Motorola-LONWORKS. In 1996, she joined Microware Systems Corporation as an Embedded Systems Software Engineer where she developed device drivers enabling infrared data transfer. From 1997 to 2000 she served as a Clinical Trials Research Associate with the Department of Radiology at the University of Michigan where she investigated the discrimination and characterization of breast cancer using 3D Doppler ultrasound imaging. Ms. Bhatti’s current research interests are in the general area of biomedical sensors and subsystems, bioMEMS, and microelectronics with an emphasis upon cochlear electrode arrays.