Saturday 23 August, 2014

‘Graphene foam’ sensor 10 times more efficient in detecting explosives

Published On: Tue, Nov 29th, 2011 | Nanotechnology | By BioNews

Graphene form sensors are ten times more efficient in sniffing out bombs and explosives compared to commercial gas detectors being used today, a new study co-led by Indian origin researcher has revealed.

A new study from Rensselaer Polytechnic Institute opens the door for a new generation of gas sensors to be used by bomb squads, law enforcement officials, defense organizations, and in various industrial settings.

The new sensor successfully and repeatedly measured ammonia (NH3) and nitrogen dioxide (NO2) at concentrations as small as 20 parts-per-million.

Made from continuous graphene nanosheets that grow into a foam-like structure about the size of a postage stamp and thickness of felt, the sensor is flexible, rugged, and finally overcomes the shortcomings that have prevented nanostructure-based gas detectors from reaching the marketplace.

“We are very excited about this new discovery, which we think could lead to new commercial gas sensors,” said Rensselaer Engineering Professor Nikhil Koratkar, who co-led the study along with Professor Hui-Ming Cheng

“So far, the sensors have shown to be significantly more sensitive at detecting ammonia and nitrogen dioxide at room temperature than the commercial gas detectors on the market today.”

Koratkar chose ammonia as a test gas to demonstrate the proof-of-concept for this new detector and nitrogen dioxide as the second test gas. Ammonium nitrate is present in many explosives and is known to gradually decompose and release trace amounts of ammonia.

Results of the study showed that the new graphene foam structure detected ammonia at 1,000 parts-per-million in 5 to 10 minutes at room temperature and atmospheric pressure. The accompanying change in the graphene’s electrical resistance was about 30 percent.

This compared favourably to commercially available conducting polymer sensors, which undergo a 30 percent resistance change in 5 to 10 minutes when exposed to 10,000 parts-per-million of ammonia.

In the same time frame and with the same change in resistance, the graphene foam detector was 10 times as sensitive.

The study has been recently published in the journal Scientific Reports, published by Nature Publishing Group.

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