Explosives detectionTerahertz waves for explosives detection
The chips generate and radiate high-frequency electromagnetic waves, called terahertz (THz) waves, which fall into a largely untapped region of the electromagnetic spectrum — between microwaves and far-infrared radiation — and which can penetrate a host of materials without the ionizing damage of X-rays; when incorporated into handheld devices, the new microchips could enable a broad range of applications in fields ranging from homeland security to wireless communications to health care, and even touchless gaming
Schematic of explosives detection using terahertz-band waves // Source: uobabylon.edu.iq
A secret agent is racing against time. He knows a bomb is nearby. He rounds a corner, spots a pile of suspicious boxes in the alleyway, and pulls out his cell phone. As he scans it over the packages, their contents appear onscreen. In the nick of time, his handy smartphone application reveals an explosive device, and the agent saves the day.
Is this science fiction? In fact, it is a real possibility, thanks to tiny inexpensive silicon microchips developed by a pair of electrical engineers at the California Institute of Technology (Caltech). The chips generate and radiate high-frequency electromagnetic waves, called terahertz (THz) waves, which fall into a largely untapped region of the electromagnetic spectrum — between microwaves and far-infrared radiation — and which can penetrate a host of materials without the ionizing damage of X-rays.
A Cal Tech release reports that when incorporated into handheld devices, the new microchips could enable a broad range of applications in fields ranging from homeland security to wireless communications to health care, and even touchless gaming. In the future, the technology may lead to noninvasive cancer diagnosis, among other applications.
“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 Ali Hajimiri, the Thomas G. Myers Professor of Electrical Engineering at Caltech. “These chips will enable a new generation of extremely versatile sensors.”
Hajimiri and postdoctoral scholar Kaushik Sengupta (Ph.D. ‘12) describe the work in the December issue of IEEE Journal of Solid-State Circuits.
Researchers have long touted the potential of the terahertz frequency range, from 0.3 to 3 THz, for scanning and imaging. Such electromagnetic waves can easily penetrate packaging materials and render image details in high resolution, and can also detect the chemical fingerprints of pharmaceutical drugs, biological weapons, or illegal drugs or explosives. Most existing terahertz systems, however, involve bulky and expensive laser setups that sometimes require exceptionally low temperatures. The potential of terahertz imaging and scanning has gone untapped because of the lack of compact, low-cost technology that can operate in the frequency range.
The release notes that finally to realize the promise of terahertz waves, Hajimiri and Sengupta used complementary metal-oxide semiconductor, or CMOS, technology, which is commonly used to make the microchips in everyday electronic devices, to design silicon chips with fully integrated functionalities and
