The underground mine atmosphere may include hazardous flammable gases, mainly methane (CH4 or firedamp), as well as life-threatening toxic gases like carbon monoxide (CO). Accurate and timely detection of such flammable and toxic gases inside mines is therefore imperative for accident prevention. Among numerous types of sensing materials, metal oxide semiconductors featuring large surface area, high crystallinity, and ease of synthesis, are studied extensively for such gas sensing applications. In this present research work, the CO and CH4 sensing characteristics of P-type CuO have been evaluated for underground mine application. The sensing performance tests were carried out and it is found that optimum sensing temperature does not depend on the morphology of the sensing material. Among the different microstructures tested, sea-urchin like CuO exhibit the best CO and CH4 sensing characteristics. The sensor can easily detect CO and CH4 gas in the concentration range of 25- 1250 ppm. The baseline stability and the effect of humidity on the sensing performance have also been studied to understand the applicability of the developed sensors in mines. Results indicate that such CuO-based chemi-resistive sensors can be very effective for the fast detection of CO and CH4 gases in humid mine atmospheres.
