<p> </p> <p>Gas sensors have many applications. Volatile organic compound (VOC) sensors are used for monitoring air quality in homes and office spaces, as well as monitoring manufacturing environments where a wide variety of VOCs can be produced. These gases can include formaldehyde, which can be toxic to humans at concentrations as low as 1 ppm. Other applications for gas sensors include flammable refrigerant detection. With the move towards developing more environmentally friendly appliances, many companies have started to use refrigerants such as R600a (isobutane) and R32 (difluoromethane), which have a much lower global warming potential (GWP) than their predecessors, such as R134a and R410a. While this move is beneficial for the environment, steps to ensure their safe usage have not been widely implemented to date. Therefore, sensors to detect VOCs at or below exposure limits, as well as flammable refrigerants at or below lower flammability limits (LFL), should be developed to ensure undue hazards are identified and mitigated. </p>