Detecting vapor traces of explosives using a self-assembled mono layer on a surface-modified MEMS capacitor and CMOS electronics

A miniature detection system, which is able to detect and selectively recognize different vapour traces of explosives, is presented in this article. It is based on surface-functionalised MEMS capacitive sensors and an extremely low noise integrated circuit. The instrument is sensitive and selective, consumes a minimum amount of energy, is very small and cheap to produce in large quantities, and is insensitive to mechanical influences. It is possible to detect 3ppt of TNT in the atmosphere (3 TNT molecules in 10⁺¹² molecules of air) at 25 °C in 1 Hz bandwidth using very small volume (few mm³) and only approx 20 mA current from a 5 V supply voltage.