Jan. 8, 1999 HOUGHTON, MI -- Two Michigan Tech researchers have found a way to move some of Nature's most delicate objects with the precision of pieces on a chess board. With their new technique, they hope to lay the foundation for constructing custom-made, living tissues, possibly even creating bridges of nerves to repair spinal cord injuries.
Assistant professors David Odde (chemical engineering) and Michael Renn (physics) use lasers to push nerve cells taken from embryonic chicks into position on a glass chip. Then the embryonic cells can be teased with a glass needle to send out connections to other nerve cells, forming a disciplined network of living tissue.
"You can potentially set up mimics of neural architectures in the body, reproducing tissues on the chip," Odde said.
"It's a non-contact method. We push the cells with a laser," Renn said, adding, "Who'd have thought that they wouldn't just heat up and die?"
You can't push just anything around with a laser. It has to be smaller than 10 microns across, or about one-tenth the width of a human hair. Renn has been experimenting in the field for several years, using a laser to guide atoms along a hollow optical fiber and then planting them on a substrate. The researchers began their collaboration when Odde heard of Renn's work and thought it might have applications in biomedical engineering.
Renn explains. "In a spinal cord injury, scar tissue blocks the nerve impulses coming from the brain," he said. "Maybe this technique could be used to build a bridge of nerve cells that could be placed over the injured area." The tissue could also be used to better understand and perhaps develop cures for neurological disorders.
And, while they haven't tried this technique, known as direct-write lithography, on other cells, they envision much broader applications. "Suppose we could deliver new cells to a damaged region, say the liver," Odde said. "Could we make some tissue equivalent that would support liver function?"
"And we can manipulate almost any kind of material, so you could mix electronic as well as biological materials on one chip," Renn said. He hopes to commercialize direct-write lithography to make circuits on an unlimited variety of substrates. Though the technique is not as fast as the photolithography now used to make computer chips, it can function on a much smaller scale, with "wires" only 20 nanometers in diameter--one-five-hundredth the width of a single neuron.
"When people ask us "What's next?" I don't know what to say," Odde said. "The possibilities are enormous. We can put an arbitrary pattern of arbitrary particles on an arbitrary surface--When I think about it, I get really excited."
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