Development of a ppb-level sensor based on catalytic combustion for total volatile organic compounds in indoor air

An adsorption/combustion-type gas sensor with low heat capacity employing Pd/γ-Al2O3 as a sensing material was fabricated by MEMS technology on a silicon substrate. The sensor was driven by low–high pulse heating at two temperatures of 200°C and 400°C. The sensor showed a large response peak to toluene upon high temperature combustion for a period of 0.4s after low temperature adsorption for 17.6s. The peak response detected toluene of low concentrations in the range of 10–1000ppb. On indoor field tests of new residential houses using the adsorption/combustion-type sensor, the total volatile organic compound concentration determined by the sensor well agreed with that obtained by GC/MS or GC/FID analysis using active carbon trapping.