Synthesis and characterization of nanocrystalline ZnO Gas Sensor

Abstract

In recent years, there is a great deal of interest in implementing sensing devices so as newlineto improve environmental and safety control of toxic and inflammable gases. There is also an newlineimmense need for the development of gas sensors which have numerous applications in newlineautomotive and industrial manufacturing, medical diagnostics and health care, defense and newlinesecurity, detection of harmful gases in mines, grading of agro-products like coffee and spices, newlinein packaging quality control, in weather stations, etc .The Semiconducting metal oxide gas newlinesensors work on the principle of change in physical and chemical properties of their sensing newlinematerials when exposed to different gas atmospheres. Semiconducting metal oxide gas newlinesensors have been studied extensively owing to their advantages of robust nature, moisture newlineimperviousness and temperature influence, simple interface electronics, quick response time newlineand recovery time. Semiconducting metal oxides include tin oxide, indium oxide, zinc oxide, newlinetungsten oxide and iron oxide. These materials have been useful to detect various gases at newlinetheir ppm level of concentrations. The sensitivity of these devices is based on the dependence newlineof the conductivity of metal oxides on the gas/surrounding atmosphere. newlineIn general, the sensors will provide an interface between the electronic equipment and newlinethe physical world typically by converting nonelectrical physical or chemical quantities into newlineelectrical signals. Metal oxide semiconductor based sensors are found to be useful for newlinedetecting toxic and combustible gases at low concentration levels, owing to their low newlineproduction cost, high sensitivity and long-term stability. The widely accepted model for gas newlinesensing mechanism is based on changes in electrical resistance of metal oxide newlinesemiconductors due to adsorption of gaseous species on the surface.