Development of SAW-based multi-gas sensor for simultaneous detection of CO2 and NO2

Novel scheme to improve SnO2/SAW sensor performance for NO2 gas by detuning the sensor oscillator frequency

“…However the concentration of NO 2 gas was too high (>100 ppm) and selectivity issue was not even accounted [9]. Other reports utilized metal oxides or bilayer structure of polymers and metal oxides as sensing layers for NO 2 gas detection [13,6,14,15]. However, the obtained results were not promising due to slow response and recovery speed and lack of selectivity [13,6,14,15].…”

“…Different sensing techniques have been used for the detection of NO 2 gas like Chemiresistive, Electrochemical, Optical, Acoustic, Chromatography, etc. [1,[4][5][6][7]. However surface acoustic wave (SAW) is the most suitable technique for the detection of toxic gases because of high sensitivity, fast response speed, good reliability, low cost, real time measurement and wireless sensing in inaccessible areas [8].…”

“…Other reports utilized metal oxides or bilayer structure of polymers and metal oxides as sensing layers for NO 2 gas detection [13,6,14,15]. However, the obtained results were not promising due to slow response and recovery speed and lack of selectivity [13,6,14,15]. Love wave SAW devices with ZnO as guiding layer and single walled carbon nanotubes as sensing layer were also utilized for the detection of NO 2 gas [16].…”

Surface Acoustic Wave Based Magnetic Sensors

“…A common extrinsic sensor concept utilizes selective thin films on top of the delay line leading to a change in mass by the measurand [13,25]. This can be, for example, a thin film with high CO2 solubility and selectivity [26]. As CO2 dissolves into the film, the additional mass load causes a detectable phase shift in the SAW.…”

Miniature low-power IR monitor for methane detection

“…To avoid gas accidents, obtaining information about concentration variations of a particular gas becomes critical. Detection of methane gas is extremely important for safety reasons in the oil and gas industries, water treatment plants, landfill sites, and in commercial or domestic environments [1][2][3][4], where methane gas may filter up through the ground and create an explosion hazard (the lower explosive limit, LEL, for methane is 5% by volume methane gas). Portable gas detectors for gas leaks are clearly important in a number of these applications, but they must be of a low-cost design for widespread use and availability.…”