A pair of researchers at the California Institute of Technology have hacked conventional chip hardware to create a device that they say is small and affordable and that can see short distances beneath certain materials (not thick metal, for example). The device can also pick up the signatures of explosives, chemical weapons and drugs, as well as identify skin cancer.
It gets better, according to its inventors: Even though the system uses the electromagnetic spectrum (on which reside dangerous X-rays), the high-frequency beams are non-ionizing, which means they present little potential for causing cancer.
A working prototype has been built by Ali Hajimiri, a professor of electrical engineering, and postdoctoral scholar Kaushik Sengupta, both of Caltech. They got a set of CMOS chips to work in unison to create invisible beams in the little-used terahertz range of the spectrum.
It’s well known that terahertz waves penetrate fabric, cardboard and even skin, returning surprisingly detailed images of whatever lies immediately below. But to date, scientists have been creating “an elephant” of a terahertz machine – big and expensive, said Hajimiri, who talks rapidly and fluidly of this technology, as if he’s perfecting his elevator pitch to would-be investors.
“We took the ‘ant’ approach,” said Hajimiri. If a personal-sized terahertz device was possible, he said, it would have to use computer chips, all of which emanate electromagnetic waves at frequencies related to how fast they process information. The problem is, no chip produces terahertz waves – they’re just too high.
Instead, Hajimiri and Sengupta employed a quirk of physics. By positioning each chip just so and operating them at just the right frequencies, they created a beam that was literally greater than the sum of its parts – 300 times greater, said Hajimiri.
“Working together, the ants can do anything the elephant can do, and more,” said Hajimiri.
A terahertz signal from a phone, he said, could wirelessly transmit hundreds of gigabytes per seconds. True, the receiving device would have to be within centimeters of the sender, but the entire contents of most hard drives could be transferred before you’ve finished reading this paragraph.
Dermatologists could more accurately and almost instantaneously diagnose melanoma using a phone or tablet with a terahertz transceiver. Melanoma, deadly scourge that it is, gives itself away when you aim a terahertz signal at it. It reflects the beam differently than does healthy skin.
It is weird to think about using a form of radiation flowing from a phone to spot skin cancer, but Hajimiri maintains the invention’s safety.
“An X-ray is like a bullet – comparatively few rays at high velocity, high energy. It smashes through things,” he said. “Terahertz waves are low-energy. It’s more like pouring sand.” The target is getting hit with low-energy “material,” but a lot of it, resulting in a finely detailed image resulting in fewer negative side effects (like DNA damage).
The technology, sufficiently powered up to see greater distances, could change games, advertising and even TV programming in remarkable ways.
Microsoft’s “touchless” game system, Kinect for Xbox 360, reads body movement and placement using invisible beams, not unlike the terahertz prototype. The difference is that Kinect sees players the way people are depicted in Minecraft – blocky and undifferentiated.
Hajimiri says a terahertz version of Kinect would see far more detail.
“It would know how angry you were,” he said. Forget about Nielsen diaries; advertisers and TV executives could gauge their success by how often you are blinking.
The Caltech team is still experimenting with the technology, so there are unknowns, like exactly how much power larger tasks would need. But Hajimiri said the prototype can see into a FedEx box using only 10 milliamps, a fraction of what a smartphone’s power amplifier creates without breaking a sweat.
“The core concept has been demonstrated,” he said. “There are no fundamental hurdles to commercializing this technology.” Already savvy in the world of empire-building, Hajimiri hedged when asked if he’s gotten any nibbles.
“We’ve had several contacts. Security is one. Gaming applications is another.”