Surface-Functionalized COMB Capacitive Sensors and CMOS Electronics for Vapor Trace Detection of Explosives

In this paper, we present a miniature detection system, which is able to detect and selectively recognize different vapor traces of explosives. It is based on surface-functionalized array of COMB capacitive sensors and extremely low noise integrated electronics. The measurement system is sensitive and selective, consumes minimum amount of energy, is very small and cheap to produce in large quantities, and is insensitive to environmental influences. Owing to extremely low noise electronics and selective modification of COMB capacitor surfaces, it is possible to detect less than 3.5 ppt of TNT in the atmosphere (three TNT molecules in 10+¹² molecules of air and 10 times better for RDX) at 25°C in one second using very small volume (few mm³). The measurement system needs only approximately 20 mA current at 5 V supply voltage.