DoE Spearheads Collaboration on Retinal Prostheses

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With the help of the U.S. Department of Energy and other funding agencies, several national laboratories, universities, and commercial firms are collaborating on retinal prosthesis technology development. The U.S. Department of Energy's Office of Biological and Environmental Research recently issued a $9 million, three-year grant for the development of retinal implant technology. The money was award to five national laboratories, two universities, and Second Sight, LLC of Valencia, CA. The goal of the project is to develop electrode arrays with increased resolution from 100 to 1000 elements by fiscal year 2004.

The University of Southern California's Retinal Prosthesis Group, led by Mark Humayun, will implant the devices and test their effectiveness. North Carolina State University will develop the in-situ medical electronics. The five national labs involved are Argonne, which is investigating diamond-based electrode arrays and biocompatible coatings, Lawrence Livermore, which is looking into rubberized arrays, Los Alamos, which is modeling neural pathways in the visual system, Sandia, which is researching MEMS chips fabricated with lithography, electroplating, and molding, and Oak Ridge, which is managing the multilaboratory effort. Second Sight will commercially produce the finished system.

As part of this effort, DoE's Medical Sciences Division is planning the
First U.S. Department of Energy International Symposium on Artificial Sight, to be held in Fort Lauderdale, FL next month. The purpose of the symposium is to provide a forum for research, discussions, and clinical advances in the field of artificial vision, especially multielectrode array retinal prostheses.

Peter Krulevitch, a scientist at Lawrence Livermore National Laboratory, has been collaborating on the retinal device with colleagues at Oak Ridge, Argonne, Sandia, and Los Alamos labs, USC and UC Santa Cruz, and Second Sight. His multidisciplinary team includes lead engineer Mariam Maghribi, fabrication technician Julie Hamilton, instrumentation engineer Courtney Davidson, MEMS guru Dennis Polla, senior engineering associate Bill Benett, and summer student Armando Tovar. Elias Greenbaum at Oak Ridge is the principal investigator on the grant. The USC clinical work is funded by the National Institutes of Health as well as the DOE.

Expertise at LLNL is being tapped to develop a flexible microelectrode array that is able to conform to the curved shape of the retina without damaging retinal tissue, and to integrate electronics developed by UC Santa Cruz. Initial prototypes with nine electrodes were tested in early durability and ergonomics studies. According to Krulevitch, the main objective of the DOE project is to try to increase the number of viable electrodes to 1000 on a square device that measures 4 millimeters on a side. "The DOE project is funded for three years, and is near its half-way point," he says. "We hope to have an approach that is scalable to 1000 electrodes one and one half years from now."

Krulevitch and colleagues have pioneered the use of a form of silicone rubber called polydimethylsiloxane (PDMS), in fabricating hybrid integrated microsystems for biomedical applications. In particular, the lab has worked on "metalization" - applying metals for electronics and electrodes to PDMS for implant devices. "It's our important contribution to this project," Krulevitch says. "We've developed a technique for fabricating metal lines that can be stretched."

Krulevitch has been encouraged by early results on the retinal device. The team did some very preliminary tests at USC's Doheny Eye Institute, mostly to see how easily the prostheses were handled in surgery. They now have a second-generation device that they are about to test at Doheny. "We will be testing conformation to the shape of the retina, device robustness during implantation, and device ergonomics during surgery," Krulevitch says.

The First U.S. Department of Energy International Symposium on Artificial Sight will be held Friday, May 2, 2003 at the Fort Lauderdale Marriott North, Fort Lauderdale, FL. The Symposium will be held in conjunction with the annual meeting of the Association for Research in Vision and Ophthalmology (ARVO). The morning session of the Symposium will provide an overview of the field. The afternoon session will focus on in-depth talks on the engineering and scientific hurdles that need to be addressed. Mark Humayun, of the Doheny Retina Institute, and Elias Greenbaum, of Oak Ridge National Laboratory, will co-chair the event.


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