Tiny Sensors to Detect Explosives, Bio Weapons, Rotten Food

Researchers at the  Naval Research Laboratory (NRL)  – Christopher Field, Junghoon Yeom, Daniel Ratchford, Hyun Jin In and Pehr E Pehrsson have figured out how to manufacture nanowires reliably using existing technology as tiny sensors built into military combat gear to detect chemical or biological weapons. The idea is to use the power of unseen sensors scattered throughout a submarine to detect radiation leaks or chemical contamination of the crew’s precious air; a cellphone, flip it open, open the app and able to detect the gas of explosives down to parts per trillion that helps to speed passengers through crowded airports. Another idea by the researchers is ability to embed sensors in a refrigerator and it could tell you exactly what was spoiling and whether it was still safe to eat.

All these technologies may now be possible due to the earlier breakthrough at the Navy’s premier research lab , the group who may be on the verge of unleashing the long-sought promise of nanotechnology. In their paper report, Nanowires of various materials and configurations have been shown to be highly effective in the detection of chemical and biological species. The report centred on a novel, nanosphere-enabled approach used in fabricating highly sensitive gas sensors based on ordered arrays of vertically aligned silicon nanowires topped with a periodically porous top electrode. The vertical array configuration helps according to them will greatly increase the sensitivity of the sensor while the pores in the top electrode layer significantly improve sensing response times by allowing analyte gases to pass through freely. They finally show a highly sensitive detection to both nitrogen dioxide (NO2) and ammonia (NH3) in humidified air. NO2 detection down to 10 parts per billion (ppb) was demonstrated and an order-of-magnitude improvement in sensor response time was shown in the detection of NH3 by the researchers.

According to the principal investigator, Christopher Field “The big thing with getting to this point is finding a way to produce this in a scaleable and reproducible fashion, but until now, nanotechnologists have had to grow their nanowires, something that is extremely difficult to do over and over again since each one is created, effectively, by hand”

“We don’t grow our wires. We actually etch our wires with silicon,” Field said, using technology similar to that used by computer chip makers. Basically, the Navy scientists etch a cluster of nanowires and put a small amount of power pulsing through them. When a molecule from an explosive’s gas or a chemical weapon brushes against the nanowires this disrupts the charge. Then scientists analysed the disruption to discover what caused it.

A provisional patent has been issued for the nanowire technology. Companies can license the technology from the Naval Research Laboratory and use the nanowire tech to build sensors and develop the algorithm to detect various substances.




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