SWNT Based Nanosensors for Wireless Detection of Explosives and Chemical Warfare Agents

The detection of concealed explosives and chemical warfare agents is an urgent need to protect the safety of people and cities around the world. This requires the development of highly sensitive, portable, and stand-off sensors. Here, we present a wireless sensing unit based on single-walled carbon nanotubes (SWNTs) integrated with complementary metal oxide semiconductor (CMOS) circuitry, which can effectively detect trace explosives and chemical agents. The response of SWNT sensors to Dinitrotoluene (DNT) (a byproduct of TNT) and Dimethyl methylphosphonate (DMMP) (an analog of nerve agent sarin) vapors is improved dramatically after decoration with single stranded-DNA (ss-DNA). The response of carbon nanotube sensors to DNT and DMMP vapors is reversible and repeatable. The nanosensors integrated on a CMOS chip are tested with DMMP (DNT) vapors with concentrations varying from 1.57 to 130.49 ppm (9.41-45.73 ppm), and the corresponding change in resistance of the SWNT sensor varied from 7.5% to 27.5% (6.53-22.76%). The detected signal is processed by off-chip components on a circuitry board and is transmitted wirelessly to a computer. This versatile sensing system provides a promising platform to detect explosives and chemical agents at a trace level in a wireless manner and stand-off distance.