Abstract: A surface acoustic wave based CO2 sensor using carbon nanotubes as the sensitive layer fabricated by combining surface acoustic wave (SAW) devices and nanotechnology. The device structure consists of the gas sensitive material between the input and output interdigital transducers (IDTs) of a SAW device. The CO2 gas gets adsorbed on nanotubes when the carbon nanotube based SAW sensor is exposed to CO2 at room temperature and/or at elevated temperature, which in turn changes conductivity of the carbon nanotube. This conductivity change will affect the velocity of the SAW traveling across the nanotubes and will give a frequency change which corresponds to the percentage of the CO2 molecules adsorbed by the nanotubes.

Abstract: A surface acoustic wave based CO2 gas sensor that utilizes zeolites or transition metals doped zeolites as a sensing layer. Such zeolites can be used “as is” or doped with metal oxide semiconductor materials such as, for example, TiO2, ZnO, SnO2, electrolytes etc. to vary the sensor sensitivity for various gases. Zeolites can be configured as thin or thick films by employing nanopowders in suitable dispersants. The addition of zeolites, catalytically modified with chromium, results in a controlled selectivity to various gases based on shape and size effects.

Abstract: A NOx gas sensor for measuring NO, NO2 and NOx gas content from automotive exhaust including a method for producing such a gas sensor. The NOx gas sensor generally includes a substrate, and a plurality of electrodes preformed and located on one side of the substrate. A platinum heater is located the other and opposite side of the substrate. A coating of nano-crystalline powders of a semi-conducting oxide material can be located and configured on the plurality of electrodes preformed on the substrate, thereby forming a gas sensor for the detection of NOx. The substrate may be composed of a ceramic material, glass, alumina and/or another type of high-melting material. The electrodes, along with the heater are preferably composed of platinum. The semi-conducting oxide material preferably comprises YMnO3 or doped YMnO3.

Abstract: A gas sensor utilizes nano-sized CeO2 and doped CeO2 particles for detecting NO, NO2 and also for studying the cross sensitivity of oxygen, un-burnt hydrocarbons, CO and CO2. Nano-crystalline powders of CeO2 and doped CeO2 are employed to configure thin films on Platinum comb type electrodes preformed on alumina substrates. Various catalytic oxides are employed to convert the NO to NO2 to get equal response to NOx gas. Gas sensing properties are measured using a dynamic chamber with a constant flow of air and NOX gas in required percentage in nitrogen gas.

Abstract: Nitrogen oxide sensors and methods for fabricating them are provided. According to an exemplary embodiment of the present invention, the method comprises providing an electrically insulating substrate having a first surface and a second surface. Two electrodes are fabricated on the first surface of the substrate. Each of the electrodes has a first end configured to receive a current and a second end. A nanopowder of a barium tungstate comprising nanoparticles of substantially uniform particle size is synthesized. A film of the barium tungstate nanopowder is deposited overlying the first surface of the substrate and in electrical contact with the second ends of the electrodes. The film is sintered and a heater is fabricated on the second surface of the substrate.