Novel Carbon Dioxide Microsensor Based on Tin Oxide Nanomaterial Doped With Copper Oxide

Carbon dioxide (CO₂) is one of the major indicators of fire and therefore its measurement is very important for low-false-alarm fire detection and emissions monitoring. However, only a limited number of CO₂ sensing materials exist due to the high chemical stability of CO₂. In this work, a novel CO₂ microsensor based on nanocrystalline tin oxide (SnO₂) doped with copper oxide (CuO) has been successfully demonstrated. The CuO-SnO₂ based CO₂ microsensors are fabricated by means of microelectromechanical systems technology and sol-gel nanomaterial-synthesis processes. At a doping level of CuO : SnO₂ = 1 : 8 (molar ratio), the resistance of the sensor has a linear response to CO₂ concentrations for the range of 1% to 4% CO₂ in air at 450^degC. This approach has demonstrated the use of SnO₂, typically used for the detection of reducing gases, in the detection of an oxidizing gas.