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UNSED COMPONENTS IN A SEALED BAG In general, semiconductor gas sensors are composed of three parts: Sensing element: including electrodes connections (RED part in the figure below. Sensor unit) Base: base materials, electrode points (BLACK part) Cap: mechanical protection, flame proof, air flow regulation (BLUE) The tin dioxide (SnO2) metal oxide semiconductor material is heated to a specific temperature (e.g. at 400oC for hydrocarbon detection). The resistance of sensing material changes rapidly according to gas concentration changes. This is caused by adsorption/desorption of oxygen and reaction between surface oxygen and gases. These reactions cause a dynamic change of electric potential on SnO2 cryastal and results in the decrease of sensor resistance under the presence of reducing gases such as CO, methane, hydrogen. The figures below indicate the sensing mechanism of the SnO2 gas sensor. Using these characteristics, the semiconductor gas sensor can be used for wide field of application. Semiconductor gas sensors have such features as "small size", "high sensitivity", "low price", "long life", and "maintenance free" and widely used mainly in the consumer markets. In addition to such features, FiS has realized a miniture size small power consumption gas sensor that can be used in a battery operated device. The single sensor can differentiate and detect several type of gases with an unique signal processing and sensor driving method. Furthermore, the improved sensing material has realized carbon dioxide detection, which was assumed to be impossible with semiconductor gas sensors. (We do not proofread any ads submitted by members) |
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