Abstract: The sensitivity and/or selectivity of a chemoresistor type gas sensor is enhanced by measuring the response of the sensing material to a gas sample while the sensing material is subjected to illumination using specially-tailored pulses of ultraviolet radiation. For a given target gas to be detected there is an optimal duration of the UV pulses to achieve peak sensitivity of the sensing material.

Abstract: A multi-storey gas sensor is constructed by stacking chemoresistor type gas sensing elements and providing holes through each sensing element so gas can pass from one sensing element to the next, through the sensing layers. A rich data set can be obtained by selecting appropriate combinations of materials for the different sensing layers and varying the operating conditions of the different gas-sensing elements by: taking measurements when different combinations of sensing layers are activated, when given sensing layers are heated to different temperatures or according to different heating profiles, and/or when selected sensing layers are exposed to UV light. Sensor sensitivity and selectivity can be increased by applying UV pulses of controlled duration, and target gas species can be detected based on the transient response of the sensing layer at onset of UV irradiation. Each sensing element may have a micro-hotplate architecture.