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Marcus D. Gingerich, Roman Akhmechet, Stuart F. Cogan, Timothy D. Plante, Douglas B. Shire, John L. Wyatt, Jr., Joseph F. Rizzo, III; A Microfabricated, Combination Flexible Circuit/Electrode Array for a Subretinal Prosthesis. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5515.
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This work is related to the efforts of the Boston Retinal Implant Project to develop a subretinal prosthesis to restore vision to the blind. The specific purpose of this presentation is to describe our efforts to develop a polyimide-based, one-piece, combination flexible-circuit and electrode array (flex-array) which interconnects the RF coil with the hermetically encased prosthesis electronics and the sputtered iridium oxide film (SIROF) stimulating electrodes. The hypothesis was that such a structure could be realized using advanced microfabrication technology.
A flexible-circuit and electrode array (flex-array) was designed in CAD based on the particular requirements of our subretinal prosthesis. A preliminary microfabrication process was designed based upon our past experience in developing polyimide-based electrode arrays, multilayered metallization and SIROF stimulating electrodes. The initial devices were microfabricated on Si carrier substrates by adapting, integrating and optimizing the aforementioned aspects of previous devices, designs, in vitro and in vivo tests, and microfabrication processes. The overall process consisted of a set of microfabrication processes and steps, including spin coating of photoresists and polyimide, microlithography, physical vapor deposition (PVD), wet and dry etching, and electroplating. The initial batch of devices to be fabricated was carefully monitored and real-time design and process changes were implemented to insure a successful outcome.
A set of microfabrication processes was successfully engineered to produce a flex-array with bonding pads on two sides. The flex-arrays were tested in vitro as well as in vivo in a Yucatan minipig for up to five and half months.
A means of fabricating a polyimide-based combination flex-array has been developed which is expected to provide basic technology for the Boston retinal prosthesis.
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