A sensor for sensing gaseous chemicals includes a substrate, a variable resistance nanocrystalline ITO thin film formed on the substrate, and electrodes electrically coupled to the thin film. A sensor array assembly includes a sensor slide and a perforated interface circuit. The interface circuit abuts and electrically couples the sensor slide. The sensor slide includes several spaced apart ITO film strips formed on a slide substrate. A common electrode is electrically coupled to a common portion of each ITO film strip providing an electrically conductive path across the common portions of each of the plurality of spaced apart ITO film strips. A discrete electrode is electrically coupled to a discrete portion of each ITO film strip. The interface circuit is configured to abut and electrically couple to the sensor slide. A conductive discrete electrode pad electrically couples each of the plurality of discrete electrodes of the sensor slide to discrete terminals on the interface circuit. A conductive common electrode pad is associated with and electrically couples the common electrode of the sensor slide to a common electrode on the interface circuit. Apertures in the interface circuit expose the thin film to the environment. Resistance changes in a detectible manner upon exposure to sensible chemicals at ambient temperature, such as 1,2,2-Trimethylpropyl methylphosphonofluoridate (soman, GD), O-Ethyl S-(2-isopropylaminoethyl) methylphosphonothiolate (VX), distilled bis(2-chloroethyl) sulfide (mustard, HD), carbonyl chloride, Phosgene (CG) and cyanogen chloride (CK), ozone, carbon monoxide, carbon dioxide, acetylene, propane, ammonia, sulfur dioxide, ethanol, methanol, volatile organic compounds and industrial toxic chemicals.