Indian scientists for the first time have developed a thermally stable and cost effective electronic polymerbased sensor for rapidly detecting nitro-aromatic chemicals, used in high energy explosives. The detection of explosives without destroying them is essential for protection and criminal investigations, minefield remediation, military applications, ammunition remediation sites, security applications and chemical sensors plays a vital role in such cases.
Though explosive poly-nitroaromatic compounds can be analyzed usually by sophisticated instrumental techniques, the requirements for quick decision making in criminology laboratories or reclaimed military sites or to detect explosive in the possession of extremists, often require simple, cheap and selective field techniques which will be nondestructive in nature. Non-destructive sensing of nitro aromatic chemicals (NACs) is difficult. While earlier studies are based mostly on photo-luminescent property, d.
To overcome such disadvantages, a team of Scientists led by Dr. Neelotpal Sen Sarma from the Institute of Advanced Study in Science and Technology,Guwahati an autonomous institute of the Department of Science & Technology, Government of India has developed a layer by layer (LBL) polymer detectorconsisting of two organic polymers — poly-2-vinyl pyridine with acrylonitrile (P2VP-Co-AN) and copolysulfone of cholesterol methacrylate with hexane (PCHMASH), which undergoes drastic change in (resistance in an ac circuit) in presence of very low concentration of NACs vapour within few seconds. Here, picric acid (PA) was chosen as the model NAC and a simple and cost effective electronic prototype was developed for visual detection of PA. A patent has been filed by the team for the novel technology funded by DeitY, GoI
“An electronic sensing device build around a polymer gas sensor can quickly detect the explosive on site” said Dr. Neelotpal Sen Sarma
The sensor device comprises of three layers–polymers copolysulfone of cholesteryl methacrylate along with 1-hexene (PCHMASH), and copolymer of poly-2-vinyl pyridine with acrylonitrile by sandwiching PCHMASH in between two P2VP-Co-AN outer layers by stainless steel (SS) mesh. The sensitivity of the system is determined by monitoring the change in the impedance response with time (sec) in presence of the vapour of the analyte (picric acid).
The trilayer polymer matrix was found to be very efficient molecular sensor for nitroaromatic chemical. The sensor device is quite simple and reversible in nature and itsresponse does not alter with varying operating temperature, in presence of other common chemicals and humidity.
The device can be operated at room temperature, has low response time and negligible interference from other chemicals. The fabrication is a very simple, is negligibly affected by humidity and the cholesterol based polymers used are biodegradable.
Indian Patent No. 3436085, Application No. 3613/DEL/2014 dt.09/12/2014 granted on 27- 04-2020.