Metal Oxide Semiconductor Gas Sensors

Some of these disadvantages can be avoided by using Ga203-based gas sensors. Ga2Q3 is an n-type semi-conducting metal oxide which is operated at the compar- 

The lifetime of metal oxide gas sensors in general is several years. Nevertheless poisoning effects can occur when exposed to silicones. An example of commercial Ga203-semiconductor gas sensors is shown in Fig. 5.32. 

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M. Graf, D. Barrettino, S. Taschini, C. Hagleitner, A. Hierlemann, and H. Baltes. Metal-Oxide-Based Monohthic Complementary Metal Oxide Semiconductor Gas Sensor Microsystem , Analytical Chemistry 76 (2004), 4437-4445. 

Metal oxide semiconductor gas sensors. The production of semi-... 

When confronted with non-linearly responding chemical sensors, forms of linearization are exploited to make the regression easier. The most common is the technique of log transforms. If a non-linear equation can be transformed into a linear one, it is said to be intrinsically linear. Using the response characteristics of a metal oxide semiconductor gas sensor as an example, an examination of transformation, linear regression, and confidence intervals can be performed. The response equation for metal oxide sensors has been theoretically determined as the following [10] ... 

Key words metal oxide semiconductors, gas sensors, environmental... 

There are many examples of CVD those that have been used for the production of metal oxide semiconductor gas sensors include atmospheric pressure CVD (APCVD), where the film synthesis is performed at or slightly above atmospheric pressure, and aerosol-assisted CVD (AACVD), where volatile or non-volatile precursors are made into an aerosol prior to deposition (Binions et al, 2004 Cross and Parkin, 2003). 

PVD has been used to fabricate metal oxide semiconductor gas sensors widely - for example, Michel et al (1995) used magnetron sputtering to produce Sn02 films. The films were shown to have a level of conductivity and, upon exposure to hydrogen, the conductivity was shown to increase. Gupta... 

In this section we review the use of metal oxide semiconductor gas sensors for the detection of environmentally important gases such as carbon monoxide, carbon dioxide, ammonia and nitrous oxides. 

Metal oxide semiconductor gas sensors have been extensively used to measure the concentration of CO in the environment. Approaches have almost exclusively focused on tin dioxide-based materials, with the focus on a variety of different scenarios. 

Wiegleb and Heitbaum (1994) reported the use of metal oxide semiconductor gas sensors for monitoring NO and CO gas concentrations in automobiles. They studied the variation in CO gas concentration over an extensive period of time. Sn02 was used to detect the change in concentration of CO (Fig. 13.6) and In203 to detect the concentration of NO. It was found that the Sn02 sensor gave results comparable to a near infra-red (NIR) optical sensor but with a faster response time. 

Various methods have been used to fabricate tin dioxide metal oxide semiconductor gas sensors. Riviere et al (2003) used screen-printing to produce a tin dioxide film. The composition of the printed ink was varied. The materials showed a significant response to CO gas - typically, a resistance change of 1 log (Ohm i) a QQ concentration of 300 ppm, at an operating temperature... 

Binions, R. (2007) A comparison of the gas sensing prop>erties of solid state metal oxide semiconductor gas sensors produced by atmospheric pressure chemical vapour deposition and screen printing. Measurement Science and Technology 18. 

Binions, R., Afonja, A., Dungey, S., Lewis, D. E., Parkin, I. P. and Williams, D. E. (2011) Discrimination Effects in Zeolite Modified Metal Oxide Semiconductor Gas Sensors. IEEE Sensors Journal 11,1145-51. 

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