Abstract: A surface acoustic wave device sensor configured so as to have at least two different modes of operation. An acoustic response is obtained from each of the different modes of operation. The different modes of operation are a combination of a temperature effect and a measurand effect. The measurand effect is caused by the absorption and/or adsorption of a substance into a selective coating on the piezoelectric substrate. The two different modes of operation are effected differently by the temperature effect and therefore can be used to effectively eliminate the temperature effect by simultaneously solving equations representative of the different modes of operation. The present invention eliminates the need to provide other relatively more complicated temperature compensating structure or to maintain the device at a predetermined constant temperature. The present invention can be used to detect different chemicals or substances.

Abstract: In this invention, we propose a high-sensitivity Pd/InP hydrogen sensor. First, a n-type InP semiconductor membrane is grown on a semi-insulating InP substrate. The concentration and thickness of this membrane are 2×1017cm−3 and 3000 Å, respectively. Then, Pd metal and AuGe alloy are evaporated on the surface of the membrane as the anode and cathode electrodes, respectively. Due to the catalytic performance of Pd metal, the adsorbed hydrogen molecules on the surface of the Pd metal are dissociated into hydrogen atoms. The hydrogen atoms diffuse and pass through the Pd metal and form a dipole layer at the interface between the Pd metal and the n-type InP membrane. This dipole layer will decrease the depletion width of the n-type InP membrane and further lower the metal-semiconductor Schottky barrier height. Therefore, the current-voltage (I-V) characteristics will be modulated after the introduction of hydrogen gas.

Abstract: A gas sensor, comprises a substrate, a sensor unit including a functional layer and an electrode structure, and an electric heating arrangement. An electrically conductive shielding structure is provided between the sensor unit and the electric heating arrangement in order to shield the measurement process at the sensor unit from interferences owing to the heating process.

Abstract: There are provided with a gas detecting sensor and a gas detecting device for controlling a ventilation system of a vehicle using the gas detecting sensor. The gas detecting sensor of the present invention includes two kinds of gas sensing layers separately formed and a heater assembly for heating the two sensing layers to different temperatures.

Abstract: A hydrogen sensor including a thin film sensor element formed, e.g., by metalorganic chemical vapor deposition (MOCVD) or physical vapor deposition (PVD), on a microhotplate structure. The thin film sensor element includes a film of a hydrogen-interactive metal film that reversibly interacts with hydrogen to provide a correspondingly altered response characteristic, such as optical transmissivity, electrical conductance, electrical resistance, electrical capacitance, magnetoresistance, photoconductivity, etc., relative to the response characteristic of the film in the absence of hydrogen. The hydrogen-interactive metal film may be overcoated with a thin film hydrogen-permeable barrier layer to protect the hydrogen-interactive film from deleterious interaction with non-hydrogen species. The hydrogen sensor of the invention may be usefully employed for the detection of hydrogen in an environment susceptible to the incursion or generation of hydrogen and may be conveniently configured as a hand-held apparatus.

Abstract: The present invention provides a gas sensor element having properties capable of detecting methane and carbon monoxide selectively with 1 sensor by improving gas selectivity of the semiconductor gas sensor. The present invention relates to a gas sensor element, which has a carbon monoxide sensor layer with an ability to function as a catalyst film that blocks carbon monoxide, which impedes detection of methane at the underlying methane sensor, and has a layer-built structure where the surface of a methane sensor is covered with the carbon monoxide gas sensor which can be obtained by a gas-phase method.

Abstract: A central electrode 12 is arranged in a coiled heater electrode 10. They are buried in a SnO2-based inner area 6, and the entirety is covered by a filter 8. The volume of the inner area 6 is set at from 1×10−3 mm3 to 16×10−3 mm3, the total volume of the bead 4 is set at from 15×10−3 mm3 to 70×10−3 mm3, and the ratio of the total volume of the bead 4 to the volume of the inner area 6 is set at from 4 to 20 to bring the sensor resistance in CO and that in methane closer to each other and increase the selectivity from hydrogen.

Abstract: A gas sensor array for detecting individual gas constituents in a gas sensor, said array being composed of a carrier member of a non-conductive substrate having a plurality of individual sensor elements formed by semiconductor oxides being applied thereon in a planar arrangement and the array is provided with contact electrode arrangements for measuring electrical conductivity, with a heating arrangement for heating a predetermined operating temperature and with protective sheaths for protecting the arrangement against external influences along with a fastening base so that the individual operating temperatures allocated to the various sensors and wherein the differences between respective sensor signals are formed for detecting the individual gas constituents, with these differences being supplied to a processing unit. In a preferred embodiment, at least one part of the individual sensor element is composed of a &bgr;-Ga2O3 thin film.

Abstract: A gas sensing element having a sample gas chamber into which a sample gas is introduced, and a reference gas chamber into which a reference gas is introduced. A sensor cell detects a specific gas concentration in the sample gas chamber. An oxygen pump cell pump cell pumps oxygen gas from or to the sample gas chamber. An introducing passage includes at least one pinhole provided on a surface of the oxygen pump cell for introducing the measuring gas into the sample gas chamber. The surface of the oxygen pump cell faces an outside of the gas sensing element. And, a porous diffusion resistive layer is provided on the surface of the oxygen pump cell so as to cover a portion corresponding to the introducing passage, thus serving to reduce or eliminate the effects of temperature dependency upon gas sensor output for properly sized and machine pinholes.

Abstract: A gas sensor determines the presence of at least one designated gas in a gaseous environment. The gas sensor comprises a semiconductor substrate; a thin insulator layer disposed on the semiconductor substrate; a catalytic metallic gate layer disposed on the thin insulator layer; and a chemically modified protective layer disposed on the catalytic metal gate. The chemically modified layer comprises a material that protects the sensor from corrosive gases and interference from at least one foreign matter and water, alters at least one of surface chemical properties and surface physical properties of the sensor, and passes only the designated gas therethrough.

Abstract: A piezoelectric gas sensing device, comprising: (a) a piezoelectric element arranged for gas sensing exposure to a gas environment; (b) a layer of a gas-retentive support material on the piezoelectric element which is retentively effective for a gas component potentially present in the gas environment; and (c) a gas-interactive material associated with the retentive support material, and sorptively effective to form a solid interaction product in interaction with the gas component potentially present in the gas environment, with the solid interaction product imparting a changed frequency response to the piezoelectric gas sensing device, in relation to a corresponding piezoelectric gas sensing device in the absence of the solid interaction product resulting from presence of the gas component in the gas environment. The device can be utilized to detect the presence and/or concentration of a gas species such as a hydride, hydrocarbon, silane, etc. in the fluid being monitored by the device.

Abstract: Real-time and accurate detection of the concentration of hydrogen peroxide vapor supplied into a treatment vessel is made possible by a method and apparatus that permits efficient and effective sterilization, disinfection, or the like with hydrogen peroxide vapor. The concentration of hydrogen peroxide vapor in a treatment vessel is detected by a semiconductor gas sensor in a treatment system where an object to be treated is brought into contact with hydrogen peroxide vapor in a treatment vessel with the pressure fixed at a constant level.

Abstract: Provided is a mass and heat flow measurement apparatus comprising sample and reference microresonators, such as sample and reference quartz crystal microbalances; sample and reference heat flow sensors, such as sample and reference isothermal heat conduction calorimeters; and sample and reference heat sinks coupled thermally to the heat flow sensors. The apparatus may be used to measure changes in mass due to a sample on a surface of the sample microresonator and also to measure heat flows from the sample on the surface of the sample microresonator by utilizing the heat flow sensors, which are coupled thermally to the corresponding sample or reference microresonators. Also provided is a method for measuring the mass of a sample and the flow of heat from the sample to the heat sink by utilizing such apparatus.

Abstract: Methods and apparatus for screening diverse arrays of materials are provided. In one aspect, systems and methods are provided for imaging a library of materials using ultrasonic imaging techniques. The system includes one or more devices for exciting an element of the library such that acoustic waves are propagated through, and from, the element. The acoustic waves propagated from the element are detected and processed to yield a visual image of the library element. The acoustic wave data can also be processed to obtain information about the elastic properties of the library element. In another aspect, systems and methods are provided for generating acoustic waves in a tank filled with a coupling liquid. The library of materials is then placed in the tank and the surface of the coupling liquid is scanned with a laser beam. The structure of the liquid surface disturbed by the acoustic wave is recorded, the recorded disturbance being representative of the physical structure of the library.

Abstract: A gas sensor determines the presence of at least one designated gas in a gaseous environment. The gas sensor comprises a semiconductor substrate; a thin insulator layer disposed on the semiconductor substrate; a catalytic metallic gate layer disposed on the thin insulator layer; and a chemically modified protective layer disposed on the catalytic metal gate. The chemically modified layer comprises a material that protects the sensor from corrosive gases and interference from at least one foreign matter and water, alters at least one of surface chemical properties and surface physical properties of the sensor, and passes only the designated gas therethrough.

Abstract: A sensor and a sensing method for use in a gas or gaseous mixture is provided. The sensor includes a gas sensitive material, MO3-x, in which M is predominantly or exclusively MO and MO3-x, is a substoichiometric molybdenum trioxide which exhibits a response in the form of an increase or a decrease in an electrical property of the material in the presence of a gas. The gas sensitive material is in communication with two or more electrodes and is arranged for being contacted with a gas or gaseous mixture. The electrodes are in direct communication with the gas sensitive material by being in contact therewith. The sensor incorporates a temperature sensor. The sensor includes a heating element.