Tiny Tools Give New Meaning To 'Cutting Edge'

March 31, 1999

MADISON - They look more like stray computer parts than precision medical tools, but Amit Lal's research creations could give surgeons an incomparable new edge in medicine.

Lal, an electrical and computer engineer with the University of Wisconsin-Madison, has created a new class of medical cutting tools etched from wafers of silicon, using some of the same lithography techniques behind integrated circuits. His silicon blades are up to 10 times as sharp as the advanced medical tools made from metal.

The technology could lead to greater precision for highly sensitive procedures, such as cataract surgery or neurosurgery, Lal said. It could also be used in the development of a genuine first in medicine: painless needles.

"What I'm trying to do is promote a new silicon age," said Lal, who believes that integrated circuits are only scraping the surface of the material's potential. "It's the most perfect material you can find for the cost. One silicon wafer might cost $15 bucks, and it is practically flawless structurally."

Silicon micro-machines -- also called micro-electromechanical systems, or MEMS -- are projected to routinely find applications in industries such as automotive and medical diagnostics. However, Lal's focus is on using silicon for high-energy actuators, and his lab is the first to explore it as a cutting material. Since it can be brittle, Lal's major research goal is to improve the material's toughness through surface treatments.

Lal's devices use an electrical process called ultrasonics, which creates extremely fast sonic vibrations that are beyond human perception. Ultrasonic medical tools have been used for years in cataract surgery, where the vibration helps break up and remove cataract tissue. Those devices, made from titanium or other high-performance metals, are very expensive, tend to overheat and need high voltage to function.

Silicon-based tools could solve those problems, and add another major advantage, Lal said. The material allows the machine-makers to integrate mechanical and electrical properties together in the same device. That means medical tools can be equipped with built-in sensors and monitors that will instantly communicate back to doctors.

Lal said this real-time feedback could greatly expand the use of ultrasonic tools, to areas such as neurosurgery where precision is paramount. "A silicon device could be designed to detect the difference between healthy and diseased tissue, and tell the doctor exactly what tissue to remove," he said.

And in ultrasonic technology, faster movement also means more precision cutting. Lal's ultrasonic applications can vibrate the working end of his cutting tools up to 200,000 times per second, roughly eight times faster than any ultrasonic devices on the market.

Lal currently has six patents pending with the Wisconsin Alumni Research Foundation on his devices, which span a wide range of uses. He has a three-year grant of $210,000 from the Whitaker Foundation for his research.

Ultrasonic industries and venture capitalists are pursuing the licensing of one of his technologies for an arterial plaque-removing tool that could improve intravascular surgery. Becton Dickinson, a major medical supply company based in New Jersey, is funding Lal's lab and intends to commercialize "painless" ultrasonic needles made from silicon.

How can a needle be painless? Lal said it's another feature of ultrasonic technology. With cutting tools, the vibrating motion cuts tissue with far less force, and the pushing or pulling of tissue is what tends to cause pain. An ultrasonic needle will create similar needle-tissue interactions that reduce pain.

The immediate applications could be for people for whom needle usage is a fact of life, such as diabetics who monitor their blood glucose daily. It could also relieve some of the severe discomfort caused by needles in cancer biopsies.

Lal has made functional prototypes of many of his devices, which he stores in petri dishes in his lab. Most of the devices are no larger than a ball-point pen or a fingernail, and are flat with a glassy-smooth finish. At their cutting end, they taper down to an extremely thin needle-like shape.

The tools are not limited to medical uses. He has also developed the world's tiniest ultrasonic fuel injector, which can break up fuel into droplets as tiny as two microns. Lal actually kept a tiny flame shooting from the tip of his fuel injector for 10 minutes.

Tiny ultrasonic engines may be useful for "laboratory on a chip" technology, where the goal is to make portable versions of high-powered lab instruments. They could be used to do on-the-spot medical analyses or measure dangerous chemicals in the air, water or soil.

In all of these near-term and distant-future applications, Lal is a firm believer that silicon will make them perform cheaper and better. It may only be finely processed sand, but Lal is almost philosophical about the stuff.

"If you look at history, a lot of the major periods were defined by the materials that came of age at the time," he said. "We had the stone age and the bronze age, and the industrial age was iron and steel. I think the next great age will be defined by silicon."
-- Brian Mattmiller, 608-262-9772

NOTE TO PHOTO EDITORS: High-resolution images of the new medical tools and engineer Amit Lal are available for downloading at: http://www.news.wisc.edu/newsphotos/lal.html

University of Wisconsin-Madison

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