Abstract: The invention relates to a method and device for determining the redox state of an anode (11), which is coated with a catalyst material or consisting thereof, associated with a high temperature fuel cell (10) or a reaction surface (16) of a reformer (13). According to the invention, at least one first resonator (3) of a piezoelectric sensor device (1) is arranged in the anode gas flow (5) of the high temperature fuel cell or in the gas flow of the reformer (13). The first resonator (3) is provided with a coating (4) which is oxidizable or reducible in the gas flow. The device also comprises a device (8) for measuring at least one modification of the resonance behaviour of the first resonator (3). The detected measuring value acts as an indicator of the redox state of the anode (11) of the high temperature fuel cell (10) or reaction surface (16) of the reformer (13).

Abstract: This present invention relates to a system for measuring resonant frequency and delay time of the quartz crystal microbalance. The system includes a transistor oscillating circuit, a switch circuit, a comparator circuit, and a control circuit. The transistor oscillating circuit comprises a quartz oscillator for generating an original oscillating signal. The switch circuit is coupled to the transistor oscillating circuit for outputting a start signal to generate the original oscillating signal. The comparator circuit is coupled to the transistor oscillating circuit for transforming the original oscillating signal to a square wave oscillating signal. The control circuit is coupled to the comparator circuit for receiving the square oscillating signal to estimate the resonant frequency and the delay time of the quartz crystal microbalance.

Abstract: In some embodiments, an oxygen concentrator may include lightweight injection molded housing components coupled to dual-pump diaphragm compressors. The oxygen concentrator may be coupled to a pressure transducer that detects a user's inhalation. The detected inhalation may signal the release of a bolus of oxygen. The sensitivity of the pressure transducer readings may be adjusted based on a detected environment. The user's breathing rate may also be determined to control the number of compressors used for increased efficiency. An ultrasonic sensor and gas flow rate meter may be used to determine an amount of oxygen being delivered to the user. Other components such as step valves and a solar panel may also be used to further conserve battery power. The oxygen concentrator may also incorporate an audio device such as a mobile phone.

Abstract: A sensor system and method for analyzing a fluid contained within an environmental control system, comprising the steps of providing a system including a passage for containing a thermal change fluid; placing a sensor including a mechanical resonator in the passage; operating the resonator to have at least a portion thereof translate through the fluid; and monitoring the response of the resonator to the fluid in the passage. A preferred sensor includes a tuning fork resonator.

Abstract: An acoustic wave sensor array device is provided for the detection, identification, and quantification of chemicals and biological elements dispersed in fluids. The sensor array device is capable of the simultaneous characterization of a fluid for multiple analytes of interest. A substrate has a plurality of channels formed therein and a sensor material layer applied in a bottom of the channels. The sensor material layer has a shear acoustic wave speed lower than a shear acoustic wave speed in said substrate. The channels may have the same material in each channel or different materials in at least two of the channels. A surface acoustic wave transducer and at least one surface acoustic wave reflector, or at least two transducers is formed on a surface of the substrate opposite the channels at a portion of the substrate that is thinned by the channels, so that the acoustic tracks of the surface acoustic wave device extend along the channels.

Abstract: A sensor includes a substrate 1 and at least one resonator, which includes an acoustic reflector 2, a piezoelectric layer 5, a first and second electrode 3, 4 placed on the same side of the piezoelectric layer 5, and a sensing layer 6. The sensing layer 6 reacts with a chemical or biological agent by absorption, adsorption, desorption or chemical reaction. As a result the individual frequency of a resonator changes and conclusions about the agent can be drawn. Such a sensor is very sensitive to an agent being sensed, especially when used in liquids.

Abstract: An ionic liquid piezoelectric gas sensor for the detection of polar and nonpolar organic vapors. The gas sensor can operate at high temperatures with a fast linear response which is also reversible. At high temperatures, the frequency change (?f) versus concentration (C) curve mirrors the Henry's gas law, such that the concentration of a gas sample in liquid solvent is proportional to the concentration or partial pressure of the sample in gas phase. The gas sensor can be used for quantitative analysis of gas vapors and determination of Henry constants.

Abstract: In a sensor for detecting a substance in liquid, recesses are provided in the upper surface of a base substrate. The recesses respectively accommodate SAW elements. A resin layer having openings is arranged such that the sensing portions at the upper surfaces of the SAW elements are exposed in the openings. A reaction film made of a material capable of binding to a target substance is also arranged so as to cover the sensing portion of at least one of the SAW elements. A liquid containing a target substance is fed from the openings.

Abstract: Prefabricated catalyzing adsorption sites are incorporated into small oscillators. In one embodiment, the sites are formed of precisely positioned gold anchors on surface micromachined oscillators. The micromachined oscillators may be formed of silicon, such as polysilicon, or silicon nitride in various embodiments. The sites allow special control of chemical surface functionality for the detection of analytes of interest. Thiolate molecules may be adsorbed from solution onto the gold anchors, creating a dense thiol monolayer with a tail end group pointing outwards from the surface of the gold anchor. This results in a thiolate self-assembled monolayer (SAM), creating a strong interaction between the functional group and the gold anchor.

Abstract: A sensor for detecting an analyte in liquid includes a base substrate provided with openings and electrode lands on one surface thereof and SAW elements each provided with a sensing portion having at least one IDT electrode on one side. The SAW elements are mounted on the base substrate with bump electrodes by a flip-chip bonding method so that the sensing portions of the SAW elements face the openings of the base substrate. At least one of the sensing portions is coated with a reaction membrane which binds to an analyte.

Abstract: A chemical sensing system has: an interrogation unit operable to wirelessly transmit an interrogation signal and wirelessly receive a response; an environmentally sealed container for holding a chemical analyte; a sensor array unit in fluid communication with the analyte disposed within the container, where the sensor array unit is operable to generate a response in the presence of a chemical stimulus; and a passive responder unit connected with the sensor array unit, the responder unit being powered from the interrogation signal, where the responder unit is operable to wirelessly receive the interrogation signal and wirelessly transmit the response to the interrogation signal to the interrogation unit.

Abstract: A method of analyzing a gas specimen mixture includes measuring the concentrations of inert components in the gas specimen mixture and the pressure and temperature of the gas specimen mixture. A number of sample gas mixtures are generated with varying percentages of hydrocarbon gases, each including the measured inert component concentrations. For each generated sample gas mixture, the method includes calculating the speed of sound therein based on the measured pressure and temperature and the particular percentages of hydrocarbon gases therein, measuring the speed of sound in the gas specimen mixture, and iteratively comparing the measured speed of sound with the calculated speed of sound in different sample gas mixtures until convergence for a particular sample gas mixture. The molecular weight of the particular sample gas mixture is calculated, and set the molecular weight of the gas specimen mixture to the calculated molecular weight.

Abstract: A system for monitoring a fluid in an environmental control system includes a mechanical resonator positioned for contacting a thermal change fluid. In some embodiments, the mechanical resonator is positioned in a passage for containing the thermal change fluid. Suitable thermal change fluids include an R-134A refrigerant, a mineral oil, an ester lubricant or a mixture thereof; a superheated refrigerant; or an elevated pressure and elevated temperature vapor, an elevated pressure liquid, a reduced pressure liquid, a reduced pressure vapor and combinations thereof. The mechanical resonator can be a flexural resonator or a torsion resonator. In some embodiments, the mechanical resonator is a tuning fork resonator. Methods of the invention include monitoring a response of the mechanical resonator to the thermal change fluid. In some embodiments, at least a portion of the mechanical resonator is translated through the thermal change fluid and the response of the resonator to the fluid is monitored.

Abstract: Sensors for determining the ambient amount (e.g., concentration) of a chemical (e.g., molecular hydrogen in a gas or vapor) are disclosed. Preferred embodiments of these sensors comprise a dense thin metal (e.g., palladium or a palladium alloy) film disposed on a microcantilever beam that is suspended above a stationary baseplate. The dense thin metal film is configured to absorb, for example, hydrogen, thereby causing the film to expand which in turn causes the microcantilever beam to deform. The deformation can be measured, for example, as a change in capacitance between the microcantilever beam and the stationary baseplate. The measured change in capacitance is indicative of the ambient hydrogen concentration.

Abstract: A micro mass measuring apparatus includes a cantilever on which a subject is attached, a piezoelectric element formed on the cantilever, an oscillation circuit for actively vibrating the cantilever and providing a varied resonance frequency by the subject, and a frequency measuring device for measuring a resonance frequency of the cantilever.

Abstract: The invention provides a contactless sensor device operable for sensing water vapor or a predetermined chemical vapor including a thin film, wherein the thin film includes a nanostructured sensing layer and a soft magnetic layer disposed directly adjacent to the nanostructured sensing layer. The thin film has a first mass, a first density, and a first magnetostrictive resonance frequency prior to the nanostructured sensing layer adsorbing a predetermined amount of a predetermined vapor and a second mass, a second density, and a second magnetostrictive resonance frequency subsequent to the nanostructured sensing layer adsorbing the predetermined amount of the predetermined vapor. The sensor device also includes a driving coil disposed indirectly adjacent to and at a predetermined distance from the thin film, the driving coil operable for generating an alternating-current magnetic field used to query a shift in the magnetostrictive resonance frequency of the thin film.

Abstract: A measurement head particularly for borehole use can measure multiple parameters with no electronics in the head and only a single conductor cable. Double-ended tuning forks (26, 28 and 38, 40) in the head are arranged to respond to different parameters such as temperature and pressure by adjusting their resonant frequencies. A drive signal on the conductor (50) is applied to transducers (30, 32, 42, 44) on all the tuning forks and those whose instantaneous resonant frequency is close will resonate. The signal is removed and the transducers return a decaying signal at the resonant frequency along the conductor. Other drive frequencies are tried, to locate the other sensors whose frequency ranges are separate.

Abstract: A hydrogen detecting system is characterized by a passive surface acoustic wave (SAW) sensor. The sensor includes a piezoelectric substrate having a self assembled monolayer arranged on at least a portion of the substrate to create a hydrophobic surface. A palladium nanocluster thin film is deposited on the monolayer and an interdigital SAW transducer is disposed upon the piezoelectric substrate for conversion of an RF signal into an acoustic wave and vice versa. At least one additional SAW element is also disposed on the substrate and spaced from the SAW transducer. The SAW element receives a signal from the SAW transducer and produces a response signal. The response signal is modified by the palladium nanocluster film due to a change in conductivity of the palladium nanocluster film upon exposure to hydrogen. This change in the response signal is measured by an interrogator, and yields a measure of the hydrogen concentration to which the sensor was exposed.

Abstract: A sensor system immersible in an ambient-fluid for sensing at least two conditions of the ambient fluid, includes a sealed chamber filled with a reference fluid of a known composition and/or pressure, and two acoustic transmission channels, one including the reference fluid, and the other including the ambient fluid. Measuring circuitry measures (a) the transit time of an energy wave through one transmission channel to determine the temperature of the fluid within the sealed chamber and thereby the temperature of the ambient fluid; and (b) the transit time of an energy wave through the other transmission channel to determine the composition and/or the pressure of the ambient fluid.

Abstract: An optoacoustic sensor for detecting one or more target gases includes a body featuring halves containing measurement cells. Each measurement cell is in communication with a light source and a microphone as well as the ambient atmosphere. Evaluation and control electronics are in communication with the light sources and the microphones sequentially illuminate the first and second light sources so that a measurement signal due to optoacoustic pressure variations from a target gas is generated by the microphone of the illuminated or gas active cell and a compensation signal is generated by the microphone of the non-illuminated or gas inactive cell. The compensation signal is subtracted from the measurement signal by the evaluation and control electronics to provide a sensor output signal.

Abstract: A gas concentration measurement instrument comprises: ultrasonic wave transmitting means for transmitting an ultrasonic wave according to an ultrasonic wave generation signal composed of a group of rectangular pulse waves; ultrasonic wave receiving means for converting the ultrasonic wave transmitted through the gas in the measurement region into an electric signal to use it as an ultrasonic wave reception signal; and gas concentration measuring means for measuring the signal output time when the ultrasonic wave generation signal is outputted, generating an envelope processing signal by subjecting the ultrasonic wave reception signal to an envelope extracting processing, measuring the threshold fall time when the envelope processing signal decreases below a predetermined threshold after exceeding the threshold, and measuring the difference between the threshold fall time and the signal output time as change in the gas concentration.

Abstract: A chemical sensing system has: an interrogation unit operable to wirelessly transmit an interrogation signal and wirelessly receive a response; an environmentally sealed container for holding a chemical analyte; a sensor array unit in fluid communication with the analyte disposed within the container, where the sensor array unit is operable to generate a response in the presence of a chemical stimulus; and a passive responder unit connected with the sensor array unit, the responder unit being powered from the interrogation signal, where the responder unit is operable to wirelessly receive the interrogation signal and wirelessly transmit the response to the interrogation signal to the interrogation unit.

Abstract: An apparatus 10 and method is provided that includes a spatial array of unsteady pressure sensors 15–18 placed at predetermined axial locations x1–xN disposed axially along a pipe 14 for measuring the velocity and volumetric flow rate of a single phase or multi-phase fluid 12 having a non-negligible axial Mach number flowing in the pipe 14. The pressure sensors 15–18 provide acoustic pressure signals P1(t)–PN(t) to a signal processing unit 30 which determines the speed of sound propagating with and against the flow of the fluid 12 in the pipe 14 using acoustic spatial array signal processing techniques. The apparatus, responsive to the measured speed of sound propagating with and against the flow of the fluid, determines the velocity and the flow rate of the fluid propagating through the pipe.

Abstract: A pressure and vibration sensing apparatus designed to sense pressure together with vibration through one apparatus. The pressure and vibration sensing apparatus includes a case adapted to be mounted in a machine generating vibration and having an inlet communicated with a source of pressure, a pressure sensor sensing pressure variation in the case, and a vibrating member retractably disposed in the case to induce the pressure variation in the case when vibration is generated in the machine.

Abstract: A method of sensing the amount of a gas in a fluid flow includes operating an acoustic wave (AW) sensor at a first resonant frequency. The AW sensor includes a high temperature stable piezoelectric plate coupled to a first gas-absorbing layer. Also included is combining a fluid flow having a gas component with the first gas-absorbing layer at a temperature of at least about 500° C. At least one resonant frequency of the AW sensor is sensed. The amount of gas in the fluid flow is sensed by correlating the resonant frequency with the amount of gas absorbed in the first gas-absorbing layer. A sensor for sensing the amount of a gas in a fluid flow includes a first gas-absorbing layer, a high-temperature-stable piezoelectric plate coupled to the first gas-absorbing layer, and a controller coupled to the high-temperature-stable piezoelectric plate.

Abstract: The disclosed sensor chip includes a substrate and a moving member coupled to the substrate and disposed for movement relative to the substrate. The moving member moves relative to the substrate in a first direction and in a second direction in response to movement of the substrate. The first direction is different than the second direction. The moving member includes a plurality of receptors. The receptors are configured for selectively binding to a first measurand.

Abstract: An apparatus and method for the analysis of particles in an aerosol includes providing an inlet for the aerosol, a sample collector which accumulates particles passing through the inlet, a sample conditioning system which can vary at least one condition relating to the collected sample, a controller which causes the sample conditioning system to operate at select conditions, a measuring device for determining at least one parameter relating to the accumulated particles. The controller monitors the parameter while the condition is varied.

Abstract: The disclosed apparatus and methods allow collection of concentrated samples of content in shipping packages without unsealing the package by forcing airflow via existing hidden gaps or, if necessary, creating one by a small incision. The air is injected into the hidden gaps by either probe or socket device to disturb and agitate contents inside the package, causing the contents to loosen and blending particulates on the surface into the air stream. Airborne particles are channeled into a detection device, where the particulates are concentrated. Display and warning apparatus receive and record the analysis results from the detection device. If the analysis finds that predetermined selection and sensitivity criteria for target hazard or contraband material are met, then the warning apparatus initiates the appropriate alert protocols.

Abstract: The invention is concerned with a method and apparatus for real time analysis of gas mixtures, e g determination of air quality, including at least one resonator (1, 11), means for gas transportation to and from the resonator (1, 11), e g by diffusion or transit flow via openings (5) means for activation (2) and detection (3) of an acoustic signal within the resonator (1, 11), at least one means (7) for measurement of the temperature within the resonator (1, 11), and at least one means (4) for the determination of both the resonance frequency and the quality factor of the resonator (1,11) in real time. These entities are related to the average molecular mass and viscosity or thermal conductivity, respectively, of the gas mixture. The resonator (1, 11 may include a compliant element, e g a constricted volume (6) and an inertial element, e g ist opening (5) or may support standing acoustic waves, in which the sound wavelength is related to a physical dimension of the resonator (1, 11).

Abstract: An electronic signal relating to a sonic wave when an intended gas does not exist in air is synchronized and locked in a feedback circuit constituting a phase-locked loop (PLL). Then, an electronic signal relating to another sonic wave when the intended gas exist in the air is input into the feedback circuit to release the synchronization (lock) of the feedback circuit to measure as a given electronic signal the difference in phase of the sonic wave in the air between with and without the intended gas to be detected. The intended gas can be detected as the electronic signal due to the difference in phase of the sonic wave.

Abstract: An acoustic gas analyzer for gas mixture has an acoustic velocity meter that provides a first output dependent on a detected transmission of acoustic energy through a gas to be analyzed, a temperature probe having a probe time constant that provides a second output indicative of a measured temperature of the gas, and a calculation unit that receives the first and the second outputs and determines compositional information of the gas therefrom. A signal processor is connected between the acoustic velocity meter and the calculation unit and temporally adapts the amplitude of the first output from the meter in a manner dependent on the probe time constant and provides a temporally adapted first output for use as the first output within the calculation unit.

Abstract: A system for determining polarization of a gas comprises a container that contains the polarized gas. An oscillator circuit comprises an NMR coil that is positioned adjacent to the container. A pulse generator circuit is configured to generate an electrical pulse that may be transmitted to the optical cell through the NMR coil to excite the polarized gas responsive to a control processor. A Q-reduction circuit that is independent of the pulse generator circuit is configured to reduce oscillations in the oscillator circuit from the transmitted electrical pulse responsive to the control processor. A receive circuit is responsive to an electrical signal that is induced in the oscillator circuit due to the electromagnetic excitation of the polarized gas. The control processor is configured to determine the polarization of the gas based on the output signal of the receive circuit.

Abstract: In a sensor on the basis of surface wave components disposed in a housing with at least one surface wave component, a fluid channel and conductors for high frequency signals, the conductors are connected to coupling capacitors with capacitive coupling surface areas which are arranged opposite each other on the housing and the surface wave equipment and closely adjacent one another so that high frequency signals can be transmitted to, and from, the surface wave components.

Abstract: The measuring arrangement contains a measuring cell and a reference cell, respectively, and microphones assigned to these cells, to which microphones an electronic evaluation circuit is connected and in which a subtraction of the signals of the microphones takes place, as well as a radiation source for applying a modulated signal to the measuring cell. The modulation frequency of the radiation source coincides with the resonant frequency of the measuring cell, and the measuring cell and the reference cell are open at at least one end to the gas to and/or aerosol to be detected. The measuring arrangement is used as smoke alarm, gas alarm, fire hazard alarm or as combined smoke and gas alarm, wherein each of the measuring cells is exposed to a radiation of a wavelength at which a relevant substance to be detected is absorbent and an opto-acoustic effect is produced as a result.

Abstract: A gas sensor (10) including a measurement chamber (28) into which a gas GS is flown and a detection element main body (40) facing the measurement chamber (28). The detection element main body (40) includes an element case 42, and a protective film (48) is adhered to a bottom surface thereof. An acoustic matching plate (50) and a piezoelectric element (51) of a substantially columnar shape and a tube body (52) provided in a position surrounding the acoustic matching plate 50 and the piezoelectric element 51 are housed in the element case (42). A filler is then introduced into the element case (42), whereby the acoustic matching plate (50), the piezoelectric element (51), and the tube body (52) are sealed by a filled layer (99).

Abstract: A paramagnetic oxygen sensor and method employs a pressure sensor having a membrane extending through an air gap for a magnetic field. A piezoelectric element is mounted on the membrane. Gas chambers are formed on either side of the membrane. The gas mixture, the properties of which are to be measured, is supplied to one of the chambers. A reference gas is applied to the other chamber. A pulsating magnetic field is provided across the air gap and through the chambers containing the gas mixture and reference gas. The differing responses of the gas mixture and reference gas to the magnetic field deflect the membrane. The deflection of the membrane is sensed by the piezoelectric element. The piezoelectric element maybe operated either in a passive mode or active mode to sense the deflection of the membrane.

Abstract: The present invention provides a delay line SAW device fabricated on a lithium niobate substrate and coated with a bilayer of nanocrystalline or other nanomaterials such as nanoparticles or nanowires of palladiumn and metal free pthalocyanine which will respond to hydrogen gas in near real time, at low (room) temperature, without being affected by CO, O2, CH4 and other gases, in air ambient or controlled ambient, providing sensitivity to low ppm levels.

Abstract: A chemical sensing system has: an interrogation unit operable to wirelessly transmit an interrogation signal and wirelessly receive a response; an environmentally sealed container for holding a chemical analyte; a sensor array unit in fluid communication with the analyte disposed within the container, where the sensor array unit is operable to generate a response in the presence of a chemical stimulus; and a passive responder unit connected with the sensor array unit, the responder unit being powered from the interrogation signal, where the responder unit is operable to wirelessly receive the interrogation signal and wirelessly transmit the response to the interrogation signal to the interrogation unit.

Abstract: An apparatus 10,70 and method is provided that includes a spatial array of unsteady pressure sensors 15–18 placed at predetermined axial locations x1–xN disposed axially along a pipe 14 for measuring at least one parameter of a saturated vapor/liquid mixture 12, such as steam, flowing in the pipe 14. The pressure sensors 15–18 provide acoustic pressure signals P1(t)–PN(t) to a signal processing unit 30 which determines the speed of sound amix propagating through of the saturated vapor/liquid mixture 12 in the pipe 14 using acoustic spatial array signal processing techniques. The primary parameters to be measured include vapor/liquid concentration (i.e., steam wetness or steam quality), vapor/liquid mixture volumetric flow, mass flow, enthalpy, density and liquid droplet size. Frequency based sound speed is determined utilizing a dispersion model to determine the parameters of interest.

Abstract: Disclosed are resonant gas sensors and methods for forming and using the disclosed sensors. The sensors include a resonator including a layer comprising adsorptive nanostructures, for example carbon nanotubes, activated carbon fibers, or adsorptive nanowires. The dielectric of the resonator is in electrical communication with the layer comprising adsorptive nanostructures such that the effective resonant frequency of the resonator depends on both the dielectric constant of the dielectric as well as the dielectric constant of the adsorptive layer. In some embodiments, the nanostructures can be degassed. The sensors can detect the presence of polar gases, non-polar gases, organic vapors, and mixtures of materials with both high sensitivity and high selectivity.

Abstract: A system and method for performing rupture event scanning and other sensing operations on a sample. The method includes providing a transducer with an immobilized binding partner material and a sample material disposed thereon. The sample material is applied to the immobilized binding partner material so that, if components in the sample material have sufficient affinity for the immobilized binding partner material, bonds will form between at least some of such components and the immobilized binding partner material. The method further includes accelerating the transducer to induce bond breakage, where such accelerating is performed by applying a drive signal to the transducer. The drive signal includes a waveform having multiple frequency components that are pre-selected based on expected resonance behavior of the transducer. The method may also include analyzing an output response of the transducer in response to application of the drive signal.

Abstract: The present invention relates to remotely determining local physical parameters in a fluid-filled cavity (e.g. heart cavities, blood vessels, industrial container) by means of ultrasound waves and encapsulated or stabilised gas bubbles. A measuring method, a method of diagnostic ultrasound of the same and an apparatus for remotely determining ambient physical local parameters of a fluid-filled cavity are disclosed.

Abstract: Hydrogen gas sensors employ an epitaxial layer of the thermodynamically stable form of aluminum nitride (AlN) as the “insulator” in an MIS structure having a thin metal gate electrode suitable for catalytic dissociate of hydrogen, such as palladium, on a semiconductor substrate. The AlN is deposited by a low temperature technique known as Plasma Source Molecular Beam Epitaxy (PSMBE). When silicon (Si) is used the semiconducting substrate, the electrical behavior of the device is that of a normal nonlinear MIS capacitor. When a silicon carbide (SiC) is used, the electrical behavior of the device is that of a rectifying diode. Preferred structures are Pd/AlN/Si and Pd/AlN/SiC wherein the SiC is preferably 6H—SiC.

Abstract: A chemical agent detector utilizing surface acoustic wave (SAW) sensors for detecting the presence of a multitude of chemical agents by sampling ambient air is provided. A pressure-differential manifold having an air intake port, an exhaust port, a valve and a pump is used to draw the ambient air into the manifold to be tested. A plurality of SAW sensors mounted on sensor driver boards which are in turn mounted on the manifold come into contact with the ambient air sample. Each SAW sensor is coated with a substance that has an affinity for detecting a particular chemical agent. Each SAW sensor driver board generates a continuous RF signal which emits a frequency shift if a particular chemical agent is detected. A power cycler module turns each sensor driver board on and off such that only one sensor driver board is powered-on at a given point in time.

Abstract: A gas concentration sensor includes a measurement chamber for measuring a concentration of a specific gas component in a gas under measurement; an inflow path for allowing inflow of the gas under measurement thereinto and an outflow path for allowing outflow of the gas under measurement therefrom; a reflection wall for reflecting an acoustic wave; and an acoustic wave transmitting-receiving element having a transmitting-receiving surface adapted to transmit an acoustic wave toward the reflection wall and receive an acoustic wave reflected from the reflection wall. The concentration of the specific gas in the gas under measurement is detected on the basis of a propagation time between transmission of the acoustic wave and reception of the reflected acoustic wave. When a predetermined member having the sensor attached thereto is placed in a horizontal plane, the transmitting-receiving surface faces downward. A recess is formed in a peripheral portion of the reflection wall.

Abstract: A gas sensor includes an element case 42 with an internal peripheral surface formed as a taper surface 100. A portion of a housing section 43 surrounded by the taper surface 100 and a protective film 48 is filled with a filler 49. When the filler 49 thermally expands at high temperature, the filler 49 is subjected to a component of force in an upward direction by the taper surface 100. Therefore, projection of an element portion 44 involving deformation of the protective film 48 is suppressed, a change ?L of a propagation distance L to a reflecting section 33 is also suppressed, and a detection accuracy never decreases. In addition, reverberation is reduced.

Abstract: An ultrasonic-wave propagation-time measuring method and gas concentration sensor are disclosed in which a reception wave which has been transmitted and received by an ultrasonic element 5 is subjected to full-wave rectification in order to obtain a full-wave-rectified wave, which is then integrated by an integration circuit 37 to obtain an integral value. A peak value of the integral value is held by a peak-hold circuit 39. As to detection of gas concentration, a threshold-level calculation section 21e sets a reference value on the basis of the peak value, and a point in time when the amplitude of a reception wave having undergone full-wave rectification is judged by a comparator 43 to have reached the reference value is regarded as an arrival time. Subsequently, a gas concentration is determined on the basis of a period between the emission time and the arrival time.

Abstract: The invention is directed to a system and method for detecting defects in a manufactured object. These defects may include flaws, delaminations, voids, fractures, fissures, or cracks, among others. The system utilizes an ultrasound measurement system, a signal analyzer and an expected result. The signal analyzer compares the signal from the measurement system to the expected result. The analysis may detect a defect or measure an attribute of the manufactured object. Further, the analysis may be displayed or represented. In addition, the expected result may be generated from a model such as a wave propagation model. One embodiment of the invention is a laser ultrasound detection system in which a laser is used to generate an ultrasonic signal. The signal analyzer compares the measured ultrasonic signal to an expected result. This expected result is generated from a wave propagation model. The analysis is then displayed on a monitor.

Abstract: An acoustic wave sensor to detect an analyte, the sensor comprising a piezoelectric material including a wide bandgap semiconductor material grown using plasma source molecular beam epitaxy.

Abstract: A sensor for the measurement of carbon dioxide concentration within an air flow being input to a measuring cell (1) connected to at least one electroacoustic element (2, 3) for transmitting and receiving airborne acoustic waves within the measuring cell (1). The output signal of the sensor corresponds to the propagation velocity of these waves and an indirect measure of carbon dioxide concentration, with an automatic offset correction functionality for compensation of undesired offset variations of the signal, caused by temperature or humidity variations. Preferably, an accumulating function for minimizing the influence of the offset variations is included, which for humidity variations may consist of a material with high porosity and surface density of polar molecular groups. Temperature control of the inner sheath (4) is effected by a temperature sensor (11), a resistive heating element (12) in good thermal contact with the inner sheath (4), and a control circuit (13).