ENVIRONMENTAL AND GEOLOGIC APPLICATION OF SOLID STATE METHANE GAS SENSORS

The atmospheric concentrations of one of the key greenhouse-gases, methane (CH4), have been increasing at a variable rate for every year, with potential influence on global climate changes. Although the amount of methane released into the atmosphere is relatively small compared to other trace gases like carbon dioxide, methane is more effective at trapping heat on Earth. Recently, geologic emissions of methane have been recognized as an important component of the global sources. The characterization of the spatial and temporal variability of these emissions is an important target for future environmental research; in this respect a series of technical specifications are demanded by the scientific community, including sensor portability, low detection limit, the need of analyzing small volumes of gas. Solid State Gas Sensors is one of the monitoring technique used increasingly for environmental measurements. Metal Oxide semiconductor (SnO2, ZnO2, et. …) is used to fabricate chemical sensors for several gases, in particular methane. The potential of this technique is based on the low conductivity of the material in clean air, which increases with the methane gas concentration in the air. The interaction mechanisms of CH4 with the semiconductor are discussed for environmental applications using portable gas detectors. An important factor for high sensitivity and selectivity to methane is its manufacturing and structure and the most used growth technique is discussed in this work for future applications. Applicability for on-shore and off-shore geologic measurements is examined with the principal objective for assessment of induced changes in the atmosphere due to methane emission.