October 7, 2002

A BGU research team thinks concentrated sunlight can approach the surgical power of expensive medical lasers.

A team of scientists at Ben-Gurion University of the Negev in Israel has been experimenting with the concept of turning sunshine into a cheap and efficient medical laser that could snuff out malignant tumors.

Jeffrey M. Gordon, a professor of BGU’s department of energy and environmental physics and the project’s lead researcher, said the idea came to him in 1998 when he noticed how the exorbitant price of surgical lasers kept them out of reach for many hospitals.

The root of the problem, he said, is that most medical lasers require a complex – and expensive – means of producing high-intensity light. But much of that light energy isn’t needed in certain types of medical procedures.

“We were searching for an alternative to lasers, ultra-bright, immense power density light sources uniquely suited to photo-thermal surgery and similar medical procedures,” Gordon said.

And the answer for Gordon and his team came out of the clear blue sky – literally.

“Sunlight can be uniquely suitable for surgical use because it can be concentrated,” Gordon wrote in the latest issue of Applied Physics Letters, which carries details of the BGU team’s latest experiments.

At the heart of their experimental system is a parabolic mirror that measures about 8 inches in diameter. The dish-shaped mirror collects sunlight and concentrates the beams onto a small flat mirror suspended above the center of the dish.

The flat mirror reflects the concentrated light energy into a 1-millimeter wide fiber optic cable, which can carry the light up to 100 meters away with very little loss of energy. At the other end of the fiber optic cable, the light can be directed onto any target – against a cancerous section of a patient’s kidney, for example.

The initial performance of the setup has been excellent, Gordon said. As reported in Applied Physics Letters, the solar-powered laser has been able to produce about 5 to 8 watts of energy, similar to what some conventional medical lasers can deliver.

And in initial tests against animal tissue – fresh chicken breasts and livers – Gordon says the setup appears to function much like a medical laser.

“We have ‘killed’ up to several cubic centimeters of chicken liver in a few minutes with only a few watts of radiative power,” he said.

Gordon said such a setup uses existing and relatively inexpensive technology.

“Based on conversations I’ve had with manufacturers, I would project that if the solar surgery prototype could be mass-produced, it has the potential to cost around $1,000 per unit,” he said.

By comparison, he said traditional medical lasers can cost up to $150,000.

“There are many places in the world and countries – Southeast Asia, China, India, South America – that can’t afford laser fiber optics for surgery,” Gordon said. “We’ve been overwhelmed by the number of interested parties.”

Gordon acknowledges that the solar laser device does have several limitations when compared to traditional medical lasers. And he’s also the first to admit that the device is very far from being perfected as a surgical instrument.

But, he and his team are plugging away with their research, working with physicians from BGU’s Soroka Medical Center to develop the protocols needed to test the device on live lab animals. Gordon hopes to try experiments soon involving organs with malignant tumors in rats.

While that might take a few years to develop, Gordon notes that the device has already spawned other non-medical experiments.

At Drexel University in Philadelphia, for example, BGU’s solar collection devices are part of a Department of Energy research program to develop smaller, but more efficient, systems to convert sunlight to electrical energy. In that experiment, an array of 20 to 25 light-concentrating mirrors could perhaps generate up to 150 watts of power.

Agami Reddy, an associate professor of civil and architectural engineering at Drexel, said grouping such small arrays together could be ideal for providing electricity in rural areas, far from traditional power grids.

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