a micro - sized gas detecting device with two electrodes separated by a gap of width ranging from 1 to 500 microns , where the detection is based on emission spectroscopy of gases in an electric discharge across the gap as the gas flows through the region . the characteristic light emitted by molecules during the discharge can be detected directly with photodiodes or transferred through optical fiber and detected with remote optical sensing components . the device can have single or multiple discharge regions in an array so that light emitted can be monitored at different wavelengths simultaneously . the device can operate under gaseous pressure ranging from a few milli - torr to a few atmospheres . the device consumes little power and can be powered with an alternating current and has the potential to be battery powered .