Handheld device can see through walls

Smartphones could be equipped to see through solid objects, say Caltech electrical engineers, who have developed tiny, inexpensive terahertz imagers.

The chips generate and radiate terahertz waves – which lie between microwaves and far-infrared radiation – that can penetrate a host of materials without the ionizing damage of X-rays.

When incorporated into handheld devices, says the team, they could be used in everything from homeland security to wireless communications – even touchless gaming.

“Using the same low-cost, integrated-circuit technology that’s used to make the microchips found in our cell phones and notepads today, we have made a silicon chip that can operate at nearly 300 times their speed,” says professor Ali Hajimiri. “These chips will enable a new generation of extremely versatile sensors.”

Terahertz scanning isn’t new – it’s been used by the NYPD, for example, to scan for weapons. However, most existing systems involve bulky and expensive laser setups that sometimes require exceptionally low temperatures.

But, with IBM’s help, the Caltech team has been able to use standard CMOS technology to design silicon chips that operate at terahertz frequencies, while fitting on a fingertip. And, says the team, they boast signals more than a thousand times stronger than existing approaches, and can be dynamically programmed to point in a specific direction.

The researchers say they’ve successfully used their scanner to reveal a razor blade hidden within a piece of plastic.

“We are not just talking about a potential. We have actually demonstrated that this works,” says Hajimiri. “The first time we saw the actual images, it took our breath away.”