Medical Electronics Symposium Conference Proceedings


Authors: Daniel F. Baldwin, Ph.D., et al.
Company: Engent, Inc.
Date Published: 5/19/2004   Conference: Medical Electronics Symposium

Abstract: A chronically implantable retinal prosthesis is currently under development to restore useful vision to patients blind with degenerative retinal diseases such as age-related macular degeneration and retinitis pigmentosa. These devices electrically stimulate the remaining healthy ganglion cells in the retina in response to wirelessly transmitted video data from outside the body, thereby effectively bypassing the dying photoreceptor cells. While these devices cannot be expected to provide the high acuity vision to which we are accustomed, they should restore the independence of some blind patients in performing many of the activities of daily living.

This paper reviews the prosthesis development at the Center for Innovative Visual Rehabilitation and presents the electronics module of the retinal implant including the assembly process used to produce the device. The miniaturized, high-density form factor and biocompatibility of the modules necessitates the use of parylene passivated flex circuitry with a dense circuit pattern. The primary ASIC is mounted using a gold wire stud bumped flip chip interconnect. Chip capacitors and resistors comprise both 0603 and 0402 body sizes. Secondary power and data coils are mounted on the mother flex circuit above the flex-to-flex connection to the stimulating electrode array. In order to ensure high yielding assemblies, a unique fixturing platform has been developed to maintain planarity of the flex circuit during solder paste print, component placement, solder reflow, and interconnect encapsulation.

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