Stanford engineers develop touch-free ultrasound device for tumor detection

Stanford engineers' tricorder device uses microwaves to probe a hidden target.--Courtesy of Arbabian Lab

As scientists search for lighter, low-cost alternatives to traditional imaging tools such as MRI or CT scans, engineers at Stanford University are developing a device that uses microwaves and ultrasound to pinpoint targets without touch, potentially improving tumor detection.

The team, led by assistant professor Amin Arbabian and research professor Pierre Khuri-Yakub, created their "tricorder" device based on research for the Defense Advanced Research Projects Agency. DARPA wanted scientists to come up with a way to identify plastic explosives buried underground that are invisible to metal detectors. The detection device could not touch the ground's surface; otherwise it would trigger an explosion.

Scientists found that pulsing microwaves through a tricorder could produce a series of ultrasound pressure waves that could indicate a buried plastic explosive. The team built capacitive micromachined ultrasonic transducers, or CMUTs, to make it easier to detect weaker ultrasound signals that jumped from the buried object through the air to the detector. "What makes the tricorder the Holy Grail of detection devices is that the instrument never touches the subject," Arbabian told the Stanford Report. "All the measurements are made through the air, and that's where we've made the biggest strides."

With positive findings in tow, the team is planning to focus its research on medical applications. Stanford engineers ran an experiment with the tricorder, holding the device a foot away from fleshlike material implanted with a sample target and using brief microwave pulses to heat the material. The team found that the heat caused the material to expand and contract, detecting the target without touching the flesh.

While the research is "still at an early stage," the scientists are confident about the technology's prospects, Khuri-Yakub said. In 5 to 15 years, the technique will become "practical and widely available," he said. The device could also offer an advantage over current screening techniques for tumors, which grow additional blood vessels to spur growth. A tricorder could probe the areas, drawing on the heat to make tumors show up as ultrasound hot spots.

"We think we could develop instrumentation sufficiently sensitive to disclose the presence of tumors, and perhaps other health anomalies, much earlier than current detection systems, nonintrusively and with a handheld portable device," Arbabian said.

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