Sniffing Out Explosives

Highly sensitive explosive detection devices combine an elastic polymer material with strain-sensitive graphene

Polymeric microcantilever as seen through an optical microscope with (grey inset) SEM image of the graphene nanoplatelet film

Over the past few decades, increase in terror attacks has motivated governments and scientists into developing explosive detection devices. To detect minute traces of concealed explosives one needs a device with high sensitivity. Prof. V. Ramgopal Rao’s team at IITBNF has developed such a device by embedding graphene within a SU-8 polymer microcantilever.

Polymer cantilevers have long been used as an efficient & low-cost sensor technology, with SU-8 being a popular material choice in this regard. However, they are not sensitive enough for detection of explosives – where concentrations are in the range of parts-per-billion (ppb) in air. To improve sensitivity, the team added a layer of graphene nanoplatelets to their SU-8 cantilever. Graphene is known to have high piezoresistivity and therefore works in conjunction with the polymer electrodes to give higher sensitivity.

Mechanical and electromechanical studies on the new cantilever show that the strain-sensitive properties of graphene are maintained when integrated into the polymer structure. To use this structure for detection of explosive, one of its surfaces needs to be coated with molecules of the receptor chemical. In this case, the cantilever was tested for the presence of the explosive TNT (2,4,6-Trinitrotoluene) by using the receptor coating of 4-mercaptobenzoic acid. It successfully detected TNT vapours down to concentration levels as low as 14 ppb level. This work combines the high sensitivity of graphene with the high flexibility of polymer materials to give a promising low-cost technology for homeland security applications.

- Tejas Naik & Rajashree Nori

Work funded/supported by: Dept. of Electronics and Information Technology (DeitY) of Government of India (GoI); DAE-SRC Programme.

Published paper: Prasenjit Ray, Swapnil Pandey and V. Ramgopal Rao, "Development of Graphene Nanoplatelet embedded Polymer Microcantilever for vapour phase explosive detection applications", Journal of Applied Physics, vol. 116, pg. 124902 (2014).

Last updated on: 20-Jul-2022