A prototype handheld ultrasound device made from the battery of a remote-control car and other cheap parts is powerful enough to sear flesh in seconds and could be used by paramedics to cauterize wounds or by doctors to treat cancer.

Soldiers could someday use a similar device to stop the massive internal bleeding caused by a roadside bomb or a gunshot wound, says the device's inventor, George Lewis, a biomedical-engineering graduate student at Cornell University. Eventually, such a tool might find its way into high-end first aid kits.

The same devices could also be used to treat cancer. Doctors have been using weak ultrasound to peek inside of the body for ages, and more recently they have started using them to cook tumors, or rattle cells to slip medicine inside.

"We use low-power ultrasound to enhance drug delivery to cancer cells in the brain," says Lewis. "By using acoustic pulses from our device, we essentially agitate the spongy brain matrix and enhance drug uptake at the tumor site."

Roasting the tumors may seem far less elegant, but it could save patients from the trouble of having surgery or radiation therapy. The treatment does have some drawbacks. For example, when high-intensity focused ultrasound is used to treat prostate cancer, it may cause impotence in some cases.

Ultrasound devices that stop internal bleeding can cause collateral damage, too. Keeping their effects on the body under control is a real challenge, says engineer Larry Crum of the University of Washington, who has been working on the problem more than 15 years.

A company called Therus has been using ultrasound to seal punctured arteries since the late '90s, Crum said, but their human trials have been under controlled circumstances. It would be much harder to test an experimental device on someone who is bleeding to death.

By reverse-engineering ultrasound devices that were already on the market, Lewis discovered that all of them had the same flaw: They waste a ton of energy. Without an efficient amplifier, the devices would drain their batteries too quickly to be useful.

So Lewis made an amplifier from ultralow-resistance transistors, and was able to build a prototype that uses 95 percent of its power to make waves. By comparison, many ultrasound machines squander more than half of their juice.

The prototype's electronics are light enough to carry anywhere, but the military wants a system that is not only portable but also autonomous. Darpa is asking scientists to make a device that can automatically detect, monitor and halt deep bleeding.

Photo: George Lewis and his prototype. Credit: Robert Barker/Cornell University

Video: Cornell Media Production Group

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