Cheap, compact chip could expand T-ray scanning potential


December 12, 2012

One of the new chips was used to non-destructively image a bullet and a knife blade hidden in a stuffed toy

One of the new chips was used to non-destructively image a bullet and a knife blade hidden in a stuffed toy

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Terahertz technology (or T-Ray, for short), sounds like something out of a science fiction movie. It utilizes high-frequency terahertz waves – which are located between microwaves and far-infrared radiation on the electromagnetic spectrum – to see through solid matter without the harmful ionizing radiation of X-rays. Although T-Ray devices have yet to become compact and affordable, that could soon change thanks to new silicon microchips developed at the California Institute of Technology.

Prof. Ali Hajimiri and postdoctoral scholar Kaushik Sengupta developed the tiny T-Ray chips using industry-standard complementary metal-oxide semiconductor (CMOS) manufacturing methods. One challenge that they faced, however, was the fact that the transistors on regular silicon chips simply cannot operate at high enough frequencies to amplify a T-Ray signal. The scientists got around this limitation by tuning and coordinating the frequencies of multiple transistors on one chip, using their combined power to achieve terahertz frequencies.

Some of Caltech's new T-Ray chips, with a penny for scale

“Traditionally, people have tried to make these technologies work at very high frequencies, with large elements producing the power. Think of these as elephants,” Hajimiri explained. “Nowadays we can make a very large number of transistors that individually are not very powerful, but when combined and working in unison, can do a lot more. If these elements are synchronized – like an army of ants – they can do everything that the elephant does and then some.”

Even once the T-Ray signal could be amplified, there was still another problem – its frequency was too high to allow it to be transmitted via a normal wire antenna. Once again, the answer lay in spreading the task around. Numerous small pieces of metal were incorporated into the chip, which all worked together to turn the chip itself into the antenna.

The end result: inexpensive chips that are small enough to fit on a fingertip, operate at a speed almost 300 times faster than traditional silicon chips, and that have a directable T-Ray signal over 1,000 times stronger than that of previous technologies. According to Caltech, the chips constitute “the world's first integrated terahertz scanning arrays.”

Using the chips in a scanning device, Hajimiri and Sengupta were able to do things such as imaging a razor blade hidden inside a piece of plastic, and analyzing the fat content of a piece of chicken. Ultimately, it is hoped that such chip-equipped scanners could be used for applications such as luggage inspection, bomb or drug detection, and Star Trek tricorder-like medical imaging.

“We are not just talking about a potential,” said Hajimiri. “We have actually demonstrated that this works.”

A paper on the research was recently published in the IEEE Journal of Solid-State Circuits.

Source: California Institute of Technology

Update: This story was amended on Dec. 13, 2012, to state that X-rays don't generate harmful ionizing radiation, but are ionizing radiation.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

Where and when can I buy a couple of these chips?


how deep in flesh will they penetrate? also, can you change the penetration to reduce it? could you vary the penetration depending upon what it hits, i.e. make it show bone fractures and the muscles, ligaments, tendons like an mri does, but also limit the penetration wherever it hits bone? what will tuning the frequency do? i.e. use X freq. for tissue, Y freq. for clothing, Z freq. for metal (or different kinds of metal)

Could it be used for rock? to find inclusions or different minerals in a specimen? at what distance can it operate? can the rays be focused for distance viewing? i understand that this is a new development, but these are questions that I came up with in less than a minute and I'm sure that people will eventually be looking into the T ray's i suggest that gizmag follow up on the research.


It can't go though water so it images the skin and anything like metal, etc that it can't penetrate.

But it easily sees though clothes which is going to make a lot of women upset. But it also sees though walls and many other things depending on the material.

Inside the body like xrays isn't going to happen.


The effect of the full spectrum of T-rays is , as far as I know, not known. According to the paper abstract, this device works at only 0.28THz, not fully in the T-ray arena.

The goal of most who are looking at 'tricoder' technology is to use computer analysis of many different sensors to find out as much as possible about what they are looking at. T-rays, low level x-rays or natural radiation, ultrasound, magnetic resonance and infrared all give different types of data that can be processed with tomography and principle component analysis to give any view (at least in theory) that you want of the inside workings of a human body. You can also get more information by using sensors in front of and behind the subject, yielding reflection, transmission and absorption data. Every new sensor is welcome. The limit is still in the computer processing capability.

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