Development of an Oxide Semiconductor Thick Film Gas Sensor for the Detection of Total Volatile Organic Compounds

摘要

Since the amendment of the Building Standards Law in 2003, the installation of ventilators is compulsory in newly built houses, because many persons suffer from indoor air pollution caused by volatile organic compounds (VOCs). The goal of this research is to develop a gas sensor that can monitor the total VOC (TVOC) gases indoors and then to control the ventilator efficiently using the sensor. In order to develop a sensor that detects TVOC, the responses of four oxide semiconductor materials to 37 different VOC gases were studied. These materials showed small responses to halogenated and aliphatic hydrocarbon gases. As a result of improving the response to these gases, among four metal oxides examined, SnO_2 and WO_3 showed high sensitivities by the addition of Pd and Pt. The sensing properties of SnO_2 for halogenated hydrocarbon gases were greatly improved by the addition of 0.5 wt% Pd. The sensing properties of SnO_2 for aliphatic hydrocarbon gases were improved by the addition of 0.7 wt% Pt. In addition, a sensor element with the addition of both platinum and palladium, that is, Pt (0.5 wt%)-Pd (0.5 wt%)-SnO_2, showed a large response to many of the VOC gases examined.