SainSmart TGS2602 Air Contaminants Sensor Detector For Arduino Raspberry Pi AVR ARM Figaro The sensing element is comprised of a metal oxide semiconductor layer formed on the alumina substrate of a sensing chip together with an integrated heater. In the presence of detectable gas, sensor conductivity increases depending on gas concentration in the air. A simple electrical circuit can convert the change in conductivity to an output signal which corresponds to the gas concentration. The TGS 2602 has high sensitivity to low concentrations of odorous gases such as ammonia and H2S generated from waste materials in ofce and home environments. The sensor also has high sensitivity to low concentrations of VOCs such as toluene emitted from wood nishing and construction products.