UI scientist's artificial retina to get use in cameras, possibly even people

Silicon chips are hard, flat and brittle. Human flesh is soft, curved and yielding. They would not seem a good match for each other.

But John Rogers, a University of Illinois materials science professor, has found a way to make silicon bendable and stretchable, so that it can wrap around heart muscle to stimulate it more effectively than a pacemaker, or stretch around brain tissue, or most recently, create an artificial retina.

The retina is a hemispherical collection of photoreceptors at the back of the eye. Rogers' new retina, announced in the scientific journal Nature, shares the shape, with transistors replacing living nerve cells. With a simple lens not unlike the human eye's, it makes a camera that may have many commercial applications, including infrared, Rogers said.

It also has potential for use in human beings.

Sigurd Wagner, a Princeton University professor who is a pioneer in materials research, said Rogers is a man to watch.

"John Rogers is doing first-class work on stretchable electronics; he is a leader at the world level. He has ideas, is a top experimenter who can put to practice highly sophisticated concepts, and he gets super results," Wagner said Wednesday.

Postdoctoral researcher Heung Cho Ko actually makes the cameras, which require 80 steps over 10 days of construction – following two years of research. His name appears first on the Nature paper, along with Rogers, Mark Stoykovich, Jishou Song, Viktor Malyarchuk, Won Mook Choi, Chang-Jae Yu, Joseph Geddes, Jianliang Xiao, Shuodao Wang and Yonggang Huang.

Rogers, a fellow of the UI's Center for Advanced Study, first attacked the problem of bending single-crystal silicon.

He found a solution in 2004, in part by attaching it to a plastic or rubber surface, and in part by trimming off a ribbon of silicon embedded with electronic components, like cutting wire off a bar of steel.

He likens it to cutting a strip of paper. The same material in a different form, a 2x4, won't bend.

Flexible electronics could make for newspapers and magazines of the future, as well as foldable satellite dishes, medical diagnostic blankets full of sensors or inexpensive, wallpaper-like televisions.

But to be housed in a living being that moves, electronics also need to be stretchable.

"We can make the silicon compressible, by engineering the layouts such that the silicon buckles upward under compression. This kind of 'accordion' type of response avoids any significant strains in the silicon itself," Rogers said in an e-mail.

But in the actual detector array, he said, "things are a little bit more complicated.

"The part that actually buckles consists of very tiny 'ribbon' cables that electrically interconnect adjacent silicon detector islands. These ribbon cables consist of a sandwich structure of polymer/thin metal/polymer, conceptually like a conventional ribbon cable, only much, much smaller in dimension."

Some of the Rogers group's bioengineering ideas are being researched in rats and pigs.

Rogers isn't willing to say that his group's creation could eventually become a "bionic eye" along the lines of the "Six Million Dollar Man."

But he's not ruling it out, either.

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