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

Carbon dioxide (CO
₂
) 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 CO
₂
sensing materials exist due to the high chemical stability of CO
₂
. In this work, a novel CO
₂
microsensor based on nanocrystalline tin oxide (SnO
₂
) doped with copper oxide (CuO) has been successfully demonstrated. The CuO-SnO
₂
based CO
₂
microsensors are fabricated by means of microelectromechanical systems technology and sol-gel nanomaterial-synthesis processes. At a doping level of CuO : SnO
₂
= 1 : 8 (molar ratio), the resistance of the sensor has a linear response to CO
₂
concentrations for the range of 1% to 4% CO
₂
in air at 450
^deg
C. This approach has demonstrated the use of SnO
₂
, typically used for the detection of reducing gases, in the detection of an oxidizing gas.