A team of scientists from Stanford University is testing a new “tricorder” technology able to remotely detect abnormal matter, such as buried plastic explosives or even early stage cancers in humans, by manipulating microwaves and ultrasound. The new “radio frequency (RF)/ultrasound hybrid imaging system,” the brainchild of Assistant Professor Amin Arbabian and Research Professor Pierre Khuri-Yakub, was designed for remote detection of embedded objects in a number of different kinds of matter, including water, soil and tissue. It was developed by the Stanford electrical engineering team as part of the Defense Advanced Research Projects Agency (DARPA) project aimed at developing a system to detect plastic explosives (IEDs) hidden underground that metal detectors are unable to pick up.
The main task of the team, who recently presented their research at International Ultrasonics Symposium in Taipei, was to create a detection mechanism that would not touch the surface, so as to avoid triggering an explosion. To make their “tricorder” technology “hear” hidden objects, researchers developed a technology based on basic principles of physics, namely that electromagnetic stimulation makes material expand and contract, and that this “expansion and contraction” generates ultrasound waves that can be detected at the surface. “In a potential battlefield application, the microwaves would heat the suspect area, causing the muddy ground to expand and thus squeeze the plastic. Pulsing the microwaves would generate a series of ultrasound pressure waves that could be detected and interpreted to disclose the presence of buried plastic explosives,” Stanford said in the press release. To make it possible for the detection process to be carried out from a distance, the Stanford team built “capacitive micromachined ultrasonic transducers” to differentiate the difference in sound waves transmission in solid objects and air. “What makes the tricorder the Holy Grail of detection devices is that the instrument never touches the subject,” Arbabian said. “All the measurements are made through the air, and that’s where we’ve made the biggest strides.”
The scientists believe that the ability to detect objects remotely will greatly advance methods for detecting tumors in patients. So far their experiments have shown great potential. The Stanford team used microwave pulses to heat a flesh like tissue with an implanted sample “target” from about a foot away. The heat caused the target to contract and to send out ultrasound waves that were then measured by scientists without touching the “flesh.”“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, non-intrusively and with a handheld portable device,” Arbabian said. The team believes that their technology will eventually be more portable and less expensive than all other alternatives.“We’ve been working on this for a little over two years,” Khuri-Yakub said. “We’re still at an early stage but we’re confident that in five to ten to fifteen years, this will become practical and widely available.” The technology would actually be the size of a handheld tricorder. According to Kevin Boyle, one of the Ph.D. students on Abrabian’s team, the prototype is about the size of a deck of cards.
“The whole point is for it to be a handheld deal,” Boyle told Mic. “There’s a little package mounted on top of electronics, and the package contains CMUTs,” or capacitive micromachined ultrasonic transducers, that are used for the remote detection of embedded objects. The main constraint is finding an appropriate, portable power source, which Boyle says would probably be something like a cellphone battery. If the team wins the DARPA contract for the technology, scientists would have a handheld means of fast, internal diagnostics. Not only can they look inside the human body and the skull, but they can peer inside steel beams to check for cracks before they’re used on construction sites. “We think a lot about traumatic brain injuries,” Boyle said. “Athletes and soldiers get wounds from pressure or shock to the head, but they don’t have immediate symptoms. With concussions, you want to know if you have them so you can rest, and with soldiers in the field, it’s hard to manage that. If you have something portable, you can diagnose people in the field and not have to take time out of their duty.”
Right now, sound waves travel through air just fine, but a lot gets lost when they have to move through solids that’s why the tool used for ultrasounds has to be placed directly on skin. The Stanford team’s work would alleviate that. “What makes the tricorder the Holy Grail of detection devices is that the instrument never touches the subject,” Arbabian said in a university release. “All the measurements are made through the air, and that’s where we’ve made the biggest strides.”
According to the release, the team has been able to prove the concept by heating a flesh-like material implanted with a target they wanted to find. From a foot away, they hit the material with microwave pulses, heating it just enough (a thousandth of a degree) to find the target. “We think we could develop instrumentation sufficiently sensitive to disclose the presence of tumors, and perhaps other health anomalies, much earlier than currently detection systems, nonintrusively and with a handheld portable device,” Arbabian said in the release. While the technology is just getting off the ground and it may take five to 15 years to be used universally, what’s so exciting here is how noninvasive and easy it is. “The aim is to make this a diagnostic tool, the kind of thing you’d have a trained nurse or technician use,” Boyle told Mic. “You probably aren’t going to CVS to scan yourself for breast tumors, but having a portable, low-power device like this lower all the inconvenience and training needed to operate it. “If the Stanford team’s technology becomes widely available, we could see expensive tests, like MRIs or CT scans, being replaced by this faster, cheaper upgrade, making previously difficult tests happen in the time it takes to pick up your dry cleaning.
For more information please visit: www.stanford.edu
