DESIGN OF A RADIO-LINKED IMPLANTABLE COCHLEAR PROSTHESIS USING SURFACE-ACOUSTIC-WAVE DEVICES

Cochlear prosthesis systems for post-lingually deaf individuals (those who have become deaf due to disease or injury after having developed mature speech capability) have been available for the past decade. The se systems require the surgical implantation of an array of electrodes within the cochlea and are driven by processed sound signals from out side the body. Some of these systems supply the electrodes through the skin (percutaneous) interface with a connector that passes through th e skin while others utilize a radio link to transfer digital data acro ss the skin barrier (transcutaneous). The system described in this pap er uses an analog signal approach to the transcutaneous transfer of si x processed speech data channels using frequency multiplexing. For dat a transmission, the system utilizes a filterbank of six narrowband sur face acoustic wave (SAW) filters in the range 72-78 MHz with a 1.2-MHz channel spacing to frequency multiplex the six carrier signals, frequ ency modulated by the processed speech signals, onto a composite signa l. The same SAW filters are used in the receiver filterbank for signal separation, but are housed in a miniaturized package. The described w ireless system includes a portable transmitter and a receiver package which is to be implanted in the patient. The implanted circuits are su pplied exclusively from power transferred from outside the body via a separate 10-MHz transcutaneous link utilizing coupled antenna coils.