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A pair of electrical engineers at the California Institute of Technology (Caltech) has developed tiny, inexpensive silicon microchips that can generate and radiate high-frequency electromagnetic waves called terahertz (THz) waves or T-Rays that penetrates materials without the ionizing damage of X-rays.
Application of this technology ranges from security and communication to health care and gaming. T-Rays can sense every molecule and so can detect cancer cells, hunt for explosive devices, concealed weapons and drugs and can even measure the fat content in a chicken. “We are not just talking about a potential. We have actually demonstrated that this works,” says Ali Hajimiri, one of the engineers. “The first time we saw the actual images, it took our breath away.”
The problem with T-Ray scanners till now has been that they are huge, requiring lasers and many lenses to focus light, and cooling equipment to keep everything at operating temperatures. But the Caltech duo has managed to miniaturize a T-Ray imager cheaply.
“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 Hajimiri. “These chips will enable a new generation of extremely versatile sensors.”
Hajimiri, a professor at Caltech, and Kaushik Sengupta (PhD ’12) describe the work in the December issue of IEEE Journal of Solid-State Circuits.
Silicon chips are not designed to operate at terahertz frequencies, and the team had to harness the collective strength of many transistors operating in unison to boost the strength of the signal. “Traditionally, people have tried to make these technologies work at very high frequencies, with large elements producing the power. Think of these as elephants,” says Hajimiri. “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.”
The many challenges the team faced were met with a strong determination to see the project through to its end and an ability to view things differently. “We had to take a step back and ask, ‘Can we do this in a different way?’” says Sengupta. “Our chips are an example of the kind of innovations that can be unearthed if we blur the partitions between traditional ways of thinking about integrated circuits, electromagnetics, antennae, and the applied sciences. It is a holistic solution.”
The question that remains is whether we have the responsibility to utilize this new technology in a way that benefits mankind. Or will it be used to further degradation?