Explosives like tnt and rdx present in the atmosphere can be selectively detected by using a hand held system using micro-cantilever based sensors and ultra sensitive instrumentation. the cost of the hand held, 9v battery operated device is very low as compared to the existing big instruments. the portable system has alarm along with lcd display and measures 6 cm x 12 cm. also, it can be used by layman on field. sensitivity down to few parts per trillion is achieved with novel ultra sensitive current excitation method and novel micro-cantilever based piezoelectric sensors fabricated at cen lab, iit bombay. the whole system on chip design by using umc 180nm scaled technology has been sent for fabrication to imec, belgium.