Developing gas sensors for detection of gases causing air pollution

With the fast development of the chemical industry, the detection of air pollutants, especially in situ, is extremely important.The Agency for Toxic Substances and Disease Registry in the USA state that long-term low-level exposure (200 ppm for over 1 year) to toluene can cause damage to kidneys, memory loss and nausea. Higher levels of toluene (600 ppm for over 1 year) can cause permanent damage to the brain, and continuous exposure can result in death. At present, the most reliable way to determine concentrations of this organic vapour is in an analytical laboratory, where samples of air are sent and tested by chemical or gas chromatography techniques. These methods have the advantages of being very accurate and sensitive (down the parts per billion level), yet there are inherent delays between taking the sample and receiving the results. Therefore, a portable, sensitive, selective and reliable gas sensor has to be developed to meet this new standard.In this thesis, we aimed to develop a sensor for the detection of volatile organic compound vapors such as toluene, xylene and ethanol. The effects of relative humidity on baseline conductivity, volatile organic compound (VOC) sensitivity and adsorption kinetics of xylene vapor on metallophthalocyanine thin films have been studied.