Abstract: A gas-concentration measuring apparatus for measuring the concentration variation of gas residing in a target region The gas-concentration measuring apparatus comprises an ultrasound-transmitter adapted to transmit an ultrasound in response to an ultrasound-generating signal having a rate of voltage change equal to or greater than a slew rate of an operational amplifier, and further adapted to output the ultrasound-generating signal. An ultrasound-receiver adapted to receive the ultrasound passed through the gas residing in the target region, and further adapted to convert the received ultrasound into an electrical signal serving as a received ultrasound signal is provided. A gas-concentration determiner adapted to input the ultrasound-generating signal and the received ultrasound signal into the operational amplifier to generate an amplified transmitting-side chopping wave and an amplified receiving-side chopping wave is further provided.

Abstract: The invention includes a particle detection system that detects bioparticles in a sample utilizing a sensor device that receives photoacoustic signals from a sample. The invention includes a system for distinguishing biologically active particles from non-biologically active particles in a sample utilizing a transducer to receive a laser induced photoacoustic signal from the sample and a fluorescence detector to receive laser induced fluorescence. The invention includes a method of screening a sample for the presence of one or more particle types by subjecting a sample to laser light and measuring at least one photonic response and at least one acoustic response are measured from the sample to produce a sample composite data set which is compared to a signature data set from a control sample. The invention also includes methods for detecting a change in the particle composition within a test area.

Abstract: A method for manufacturing a flexural plate wave sensor including the steps of depositing a sacrificial material layer over a silicon substrate, depositing a membrane layer over the sacrificial material layer with the membrane layer covering the sacrificial material layer and contacting the silicon substrate, depositing a piezoelectric layer over the membrane layer, forming a first transducer on the piezoelectric layer, forming a second transducer on the piezoelectric layer, spaced from the first transducer, removing the sacrificial material layer to expose a portion of the membrane layer, and depositing an absorptive coating on the exposed portion of the membrane layer.

Abstract: A method and an apparatus for characterizing the barrier properties of an array of coatings. The method including providing a plurality of acoustic wave devices, wherein each of the plurality of acoustic wave devices comprises at least one surface, and providing a plurality of coating materials suitable for forming a plurality of coatings on the at least one surface of each of the plurality of acoustic wave devices. The method also including coating each of the plurality of acoustic wave devices with at least one of the plurality of coating materials to form a plurality of coated acoustic wave devices and measuring a predetermined output parameter of each of the plurality of coated acoustic wave devices.

Abstract: The artificial olfactory system is an ultra-sensitive and selective odor sensing system for the detection of odorant molecules down to the part per trillion level. The system includes multiple ultra sensitive frequency sensors, such as sensors based on piezoelectric substrates or micro-machined resonators, capable of detecting frequency changes resulting from the interaction of odorant molecules with the sensor. A coating applied to the sensor greatly increases the surface of interaction between the odorant molecules or biological agents and the sensor. An array of these sensors, each responding to the interaction of an odorant molecule species but in a different manner, results in different frequency shifts. An ultra sensitive frequency measurement device measures as small as part per billion shift in frequency.

Abstract: A detecting-element assembly (40) is configured such that a piezoelectric element (51) is housed in a casing body portion (43) of a casing (42), and is attached to a housing portion (22) of a flow path formation member (20) via a flange portion (41). Therefore, the path between the piezoelectric element (51) and the position of attachment of the detecting-element assembly (40) is elongated, whereby ultrasonic waves which leak into the interior of the detecting-element assembly (40) from the piezoelectric element (51) become unlikely to reflectively return from a joint. Thus, the influence of, for example, noise stemming from reflected waves is reduced, thereby enhancing the accuracy of detection. An average clearance of 1 millimeter or more is provided along the outer circumferential surface of the casing body portion (43) of the detecting-element assembly (40), whereby a problem of collected foreign matter is unlikely to occur.

Abstract: Systems and methods of monitoring thin film deposition are described. In one aspect, a thin film deposition sensor includes an acoustical resonator (e.g., a thin film bulk acoustical resonator) that has an exposed surface and is responsive to thin film material deposits on the exposed surface. A substrate clip may be configured to attach the thin film deposition sensor to a substrate. A transceiver circuit may be configured to enable the thin film deposition sensor to be interrogated wirelessly. A method of monitoring a thin film deposition on a substrate also is described.

Abstract: A molecular contamination monitor for monitoring molecular contamination on a surface of a subject surface susceptible to degradation by a molecular contaminant. The monitor includes a surface acoustic wave (SAW) device having a SAW measurement surface coated with a material that is equivalent to the subject material with respect to spontaneous contamination by a contaminant. In the preferred embodiment, the coating comprises the same material as the subject surface or a material that interacts chemically with the contaminant in an equivalent manner to the subject surface. Exemplary coatings include: photoresist, copper, silver, gold, platinum, titanium, tungsten, aluminum, nickel, metal oxides, stearic acid, silicon, gallium arsenide, gallium nitride, germanium, silicon germanium, silicon dioxide, silicon nitride, and glass. Exemplary coating methods include sputtering, CVD, ALD and misted deposition.

Abstract: A photoacoustic sensor that measures carbon black particles emitted in the exhaust gas of a vehicle traveling on a road or being tested on a dynamometer or engine stand. The sensor includes an acoustic waveguide and a pump mounted to an outlet of the waveguide. The pump pulls the gas through the waveguide. A critical orifice is mounted between the pump and the outlet. The critical orifice prevents noise generated by the pump from entering the waveguide. Optical windows are mounted at opposite ends of the waveguide. A modulated source of light is located adjacent one of the windows and irradiates the waveguide. A microphone is attached to the waveguide. The microphone detects an acoustic signal generated by absorption of the light by the particles in the gas. The acoustic signal is proportional to the mass concentration of particles in the gas. The microphone generates an electrical signal proportional to the acoustic signal.

Abstract: Systems and methods of monitoring thin film deposition are described. In one aspect, a thin film deposition sensor includes an acoustical resonator (e.g., a thin film bulk acoustical resonator) that has an exposed surface and is responsive to thin film material deposits on the exposed surface. A substrate clip may be configured to attach the thin film deposition sensor to a substrate. A transceiver circuit may be configured to enable the thin film deposition sensor to be interrogated wirelessly. A method of monitoring a thin film deposition on a substrate also is described.

Abstract: A sensor circuit for use in measuring concentrations of an analyte in a fluid is comprised of a BAW sensor, a voltage variable capacitor connected to the sensor, an input which supplies a bias warping dc voltage to the voltage variable capacitor, and a resonant oscillator circuit. The resonant oscillator circuit detects the fundamental frequency of the sensor and produces a resonant signal frequency. The bias warping dc voltage applied to the voltage variable capacitor warps the resonant frequency of the circuit away from inharmonic noise.

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: In a method for producing surface wave sensors on the basis of a surface wave building component a polymer parylene film with a thickness of 20 to 200 nm is applied to a hydrophilic sensor surface of the surface wave building component by deposition from the gas phase, whereby the hydrophilic sensor surface becomes hydrophobic, the surface is then subjected to plasma activation to render it hydrophilic and a hydrophilic sorption polymer layer is then applied to the parylene film so as to provide a surface wave sensor with a homogenous sorption polymer layer.

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: An apparatus that is configured to sense the presence of gases, vapors and liquids using acoustic waves. The apparatus comprises a first part that is configured to generate acoustic waves. The apparatus further comprises a second part having a sensing and acoustic wave guiding device, which is configured to sense the presence of such substances and propagate acoustic waves. The first part is removably fixable to the second part of the apparatus. When the first part is fixed to the second part, the acoustic waves propagate in the second part.

Abstract: Workstation, apparatuses and methods for the high-throughput synthesis, screening and/or characterization of combinatorial libraries. The invention relates to an array, which permits various high-throughput methods for synthesis, screening and/or characterization in the same array, without requiring sample transfer from the array. In a preferred embodiment, the synthesis, screening, and/or characterization steps are carried out in a highly parallel fashion, where more than one compound is synthesized, screened, and/or characterized at the same time. The invention may be practiced at the microscale. The array may comprise thermal channels, for regulating the temperature of the wells in the array. The wells of the array may comprise a membrane, which is used in various screening and characterization methods. The invention also relates to a covered array, comprising the array and an array cover, as well as an apparatus comprising the array, which comprises the array, an array cover and a stage.

Abstract: The artificial olfactory system is an ultra-sensitive and selective odor sensing system for the detection of odorant molecules down to the part per trillion level. The system includes multiple ultra sensitive frequency sensors, such as sensors based on piezoelectric substrates or micro-machined resonators, capable of detecting frequency changes resulting from the interaction of odorant molecules with the sensor. A coating applied to the sensor greatly increases the surface of interaction between the odorant molecules or biological agents and the sensor. An array of these sensors, each responding to the interaction of an odorant molecule species but in a different manner, results in different frequency shifts. An ultra sensitive frequency measurement device measures as small as part per billion shift in frequency.

Abstract: The invention relates to a method and to apparatus for thermodynamic analysis of a mixture of fluids, in which the volume of a sample of a given quantity of said mixture is caused to vary step by step and in monotonic manner, and the pressure of the sample is read at each step, the sample being stirred at each step so as to hasten the mixture reaching thermodynamic equilibrium. According to the invention, the sample is stirred by applying ultrasound to said sample by means of transducer (20). The sample can be contained in a bag (19) of flexible material immersed together with the transducer in a control fluid inside a rigid container (10). The invention can be used to determine the bubble point of a mixture of hydrocarbons.

Abstract: A method and device for detecting condensation on surfaces of structural components. A evaluation signal is generated before dewing while the structural component is cooling. A detectable film is produced on a measuring arrangement a few degrees Kelvin before the dew point is reached. The temperature is measured directly on the layer where the dew is developing.

Abstract: An apparatus to normalize a flow rate of a fluid in a main flow channel is provided. The apparatus uses a moveable member, such as a flexible membrane disposed for reciprocating displacement, to produce a constant dither flow of the fluid that is independent of fluid composition. This dither flow generates a signal output from a normalizing flow sensor that both represents a characteristic property of the fluid and a flow rate calibration factor. A similar apparatus to determine the characteristic property or flow rate calibration factor is also provided. The devices disclosed may be used in numerous industrial, process, and medical flow system applications for normalization of flow sensors and to derive other properties of a fluid.

Abstract: An apparatus and method for sensing chemical and/or biological analytes includes a deflectable arm of a microcantilever formed over and contacting a sensing element. A gaseous or liquid medium which may include the analyte being detected, is introduced to the sensing element. The sensing element undergoes volumetric expansion or contraction in the presence of the analyte sought to be detected, typically by adsorbing the analyte. The volumetric change of the sensing element causes the deflectable arm to deflect. The deflectable arm includes at least one measurable physical property which changes when the arm deflects. Detecting means are provided to measure the change in the physical property to determine the presence and amount of analyte present. An array of microcantilevers in which each microcantilever is dedicated to detecting a particular analyte which may be included in the medium, is also provided.

Abstract: The invention relates to a method for detecting a low molecular weight compound in a solution which utilizes a quartz resonator and which comprises capturing a low molecular weight compound between an adsorptive film (A) for a low molecular weight compound provided on the surface of a quartz resonator and an adsorptive film (A) for a low molecular weight compound provided on the surface of a signal enhancing material and comprises detecting the shift in frequency of the quartz resonator before and after the capture.

Abstract: An arrangement is described for the quantitative and qualitative analysis of particles in gases, especially of particles in the exhaust gas of internal combustion engines, comprising a vibrating system with at least one vibration sensor, preferably a piezoelectric resonator, which is provided with at least one collecting surface for the particles to be analyzed, a circuit for the determination of characteristic vibration parameters as well as guide and transport arrangements for the gas to be analyzed. In order to obtain as large as possible a measuring range with a linear characteristic line and therewith a great sensitivity and dynamics with respect to the mass load in the entire measuring range, there is provided a vibration sensor stationary relative to the measuring chamber, and at least one active deflecting device for the gas or the particles contained in the gas.

Abstract: A method and apparatus for measuring properties of a fluid composition in a conduit includes a mechanical resonator connected to a measurement circuit. The measurement circuit provides a variable frequency input signal to the mechanical resonator, causing the mechanical resonator to oscillate. The input signal is then sent to the mechanical resonator and swept over a selected frequency range. The mechanical resonator's response over the frequency range depends on various characteristics of the fluid being tested, such as the temperature, viscosity, and other physical properties.

Abstract: A process to determine aerosol particles in gaseous samples, specifically in the exhaust of diesel motors, includes the at least indirect deposit of aerosol particles on a piezoelectric oscillating crystal and the determination of the oscillation parameters of the piezoelectrically stimulated oscillation of the crystal. In order to assure the required reproducibility reliably and independently of the type of aerosol particles, and thus to achieve a high quality of measurements, the piezoelectric crystal is charged to oscillation during less than half the period of deposit of aerosol particles.

Abstract: A method of determining the reaction efficiency of a CVD process reactor by which a reactive gas combination entering the reactor deposits a solid reaction product as a thin film onto a substrate. The composition of the reactive gas combination is measured by an acoustic cell which is disposed downstream from the outlet port of the reactor to determine the reactor's efficiency. Determination of the reactor's efficiency allows the growth rate of the thin film to be determined as well as associated rates of the products which have been exhausted from the reactor.

Abstract: In order to achieve reproducible vibration excitation of a quartz crystal even under the technical conditions which prevail when it is used for monitoring electroplating baths, a mounting for the quartz crystal 7 is proposed. The mounting for the quartz crystal 7 has two holding elements 3, 6, 14 detachably connected to one another as a form-fit, and at least two contact elements 5, 9 on the holding elements 3, 6, 14 brought into electrical contact with the contacting surfaces 32 of the quartz crystal 7. The quartz crystal 7 is fitted with the holding elements 3, 6, 14 and/or the contact elements 5, 9 at least one of the contact elements 9 being configured as a resilient body. The at least one resilient contact element 9 has an end face 34, 134 for electrically contacting the quartz crystal 7, the size of which face corresponds roughly to the size of the quartz crystal 7.

Abstract: A mass sensor including: a connecting plate having one or more slit(s) and/or opening portion(s) formed therein and/or having a thin-walled portion and a thick-walled portion formed therein; a diaphragm joined with the connecting plate at respective side surfaces; a piezoelectric element; a sensing plate with the piezoelectric element being provided at least at one part on at least one surface of the sensing plate, which has its side surface joined with a side surface of the connecting plate in the direction perpendicular to the joining direction of the diaphragm and the connecting plate; and a sensor substrate with which at least a part of side surfaces of the connecting plate as well as the sensing plate are joined, and the diaphragm, the connecting plate, the sensing plate, and the piezoelectric element form a resonating portion.

Abstract: A transducer includes a resonant structure having a first spring-mass system extending to a connection mass or nexus to which is connected a second spring-mass system, which includes a sensing element. The two spring-mass systems vibrate in antiphase. The nexus is connected to a mechanical datum provided by a mounting by means of a semi-rigid connection member which is preferably stiffer than the first member and which can control the relative motions of the first and second spring-mass systems. The sensing element contains a re-entrant resonator constituted by a spring-mass system, which can be used to adjust the characteristics of the transducer.

Abstract: A method and apparatus for measuring the calorific value of a gas. The apparatus includes a chamber to which a gas in question, for example natural gas, is supplied through an inlet and leaves through an outlet. The speed of sound SoS at ambient temperature is measured using any suitable method such as electronic control and a calculating device and an ultra-sound emitter and an ultra-sound receiver. The ambient temperatures Ta, is observed by a temperature sensor, and a thermal conductivity sensor measures the thermal conductivity of the gas at two different temperatures above the ambient temperature. One value ThCH, of the thermal conductivity is measured at 70° C. above ambient and the other value ThCL of the thermal conductivity is measured at 50° C. above ambient. The control calculates the calorific value CV of the gas according to the formula: CV=a·ThCH+b·ThCL+C·SoS+d·Ta+e·Ta2 +f, where a, b, c, d, e and f are constants.

Abstract: A method and apparatus are provided for detecting and monitoring micro-volumetric enthalpic changes caused by molecular reactions. Micro-machining techniques are used to create very small thermally isolated masses incorporating temperature-sensitive circuitry. The thermally isolated masses are provided with a molecular layer or coating, and the temperature-sensitive circuitry provides an indication when the molecules of the coating are involved in an enthalpic reaction. The thermally isolated masses may be provided singly or in arrays and, in the latter case, the molecular coatings may differ to provide qualitative and/or quantitative assays of a substance.

Abstract: An acoustic wave based-chemical sensor utilizing a crystal substrate and a coating of at least two blended materials is disclosed. The blended materials comprise a combination of (a) a high glass transition temperature polymer or a material of high melting point, and (b) a low glass transition temperature polymer or a material having a low melting point. Transducers are connected to the crystal substrate to generate an alternating potential across the crystal substrate, which in turn causes the crystal to resonate due to the converse piezoelectric effect. The blended coating absorbs the analyte, thus changing the mass of the chemical sensor, and accordingly changing its resonant frequency. The transducers detect this change in resonant frequency to indicate that the analyte is present.

Abstract: A single particle photoacoustic absorption spectrometer for directly measuring the absorption spectra for in situ individual aerosol type particles that is comprised of an electrodynamic trap capable of suspending a charged particle in free-space in a non-intrusive manner; a source of modulated monochromatic electromagnetic radiation, e.g., a laser, and an acoustic transducer/resonator for detecting/amplifying sound waves emitted by the irradiated particle. Depending on the characteristics of the particle, a certain fraction of the electromagnetic energy will be absorbed by the particle resulting in its rapid heating and cooling at the modulation frequency. The heat generated within the particle is rapidly transferred to the surrounding air resulting in a sound wave. The intensity of the sound wave is proportional the absorbed energy by the particle.

Abstract: The use of the crystalline nanoporous form &dgr; of syndiotactic homopolymer or copolymers of styrene as sensing elements for detection of organic pollutants is disclosed as well as sensors using such polymers. The sensors so obtained are suitable for the detection in air or water of organic pollutants.

Abstract: An analyte, viscosity, or temperature sensing apparatus for operative arrangement within a time-varying magnetic field, including a sensor with an outer surface that is chemically, frictionally, or thermally responsive and adhered to a base magnetostrictive element, and a receiver to measure a first and second value for magneto-elastic emission intensity of the sensor taken at, respectively, a first and second interrogation frequency. A change in mass or a change in material stiffness of the sensor due to the responsiveness, the viscosity and mass density of a fluid therearound, or the temperature, can be identified. The receiver, alternatively, measures a plurality of successive values for magneto-elastic emission intensity of the sensor taken over an operating range of successive interrogation frequencies to identify a value for the sensor's magneto-elastic resonant frequency (a fundamental frequency or harmonic thereof).

Abstract: A method and apparatus for measuring properties of a liquid composition includes a mechanical resonator, such as a thickness shear mode resonator or a tuning fork resonator, connected to a measurement circuit. The measurement circuit provides a variable frequency input signal to the tuning fork, causing the mechanical resonator to oscillate. To test the properties of a liquid composition, the mechanical resonator is placed inside a sample well containing a small amount of the liquid. The input signal is then sent to the mechanical resonator and swept over a selected frequency range, preferably less than 1 MHz to prevent the liquid being tested from exhibiting gel-like characteristics and causing false readings. The mechanical resonator's response over the frequency range depends on various characteristics of the liquid being tested, such as the temperature, viscosity, and other physical properties.

Abstract: There is provided a double-headed mass sensor (25) in which between a first connecting plate (22A) joined to a first diaphragm (21A) at respective sides and a second connecting plate (22B) joined to a second diaphragm (21B) at respective sides, a first sensing plate (41A), on which a main element (44) is provided on at least one plane surface, is bridged, and a resonating portion comprising the diaphragms (21A), (21B), the connecting plates (22A), (22B), the first sensing plate (41A) and the main element (44) is joined to a sensor substrate (27). Change in the mass of each of the diaphragms (21A), (21B) is measured by measuring change in the resonant frequency of the resonating portion accompanying the change in the mass of the diaphragms (21A), (21B). The mass sensor of the present invention enables the easy and highly accurate measurement of a minute mass of a nanogram order including microorganisms such as bacteria and viruses, chemical substances, and the thickness of vapor-deposited films.

Abstract: A method and apparatus for improving temperature stability of surface-launched acoustic wave sensors is described. The system includes a plurality of acoustic wave delay lines or resonators coated with identical films which are physically, chemically, biologically, or otherwise sensitive to one or more target chemical or biological analytes. At least one of the delay lines or resonators, referred to herein as reference channels, is used as a frequency reference to which the oscillation frequencies of the remainder of the delay lines or resonators, referred to as sensing channels, are compared. A thin coating of material that is preferably a passivation layer not sensitive to the analytes, is disposed upon the surface-launched acoustic wave sensor. The passivation layer covers sensing films on the reference channels, blocking or impeding interaction of the sensing films and the analytes thereby.

Abstract: Provided are a measurement apparatus and a measurement system comprising sample and reference microresonators, such as sample and reference quartz crystal microbalances; sample and reference heat flow sensors; and a heat sink coupled thermally to the heat flow sensors. These may be used to measure changes in one or more properties, such as mass, due to a liquid sample on a surface of a 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 one or more properties, such as mass, of a liquid sample and the flow of heat from the sample to the heat sink by utilizing such apparatus.

Abstract: A real time nonvolatile residue (NVR) monitor operates to efficiently detect molecular contamination in a given environment. The present NVR monitor utilizes surface acoustic wave (SAW) resonators in a controlled environment which efficiently promotes deposition of NVR on the sensor surface. The SAW resonators preferably operate at a resonant frequency of approximately 200 MHz-2,000 MHz which enables the NVR monitor to detect molecular contamination on the order of 10−11 g-cm−2 to 10−13 g-cm−2. The NVR monitor utilizes active temperature control of (SAW) resonators to achieve a stable resonant frequency and to thermally separate NVR from a sample fluid contacting the SAW. The temperature control system of the NVR monitor is able to directly heat and cool the SAW resonators utilizing a thermoelectric element to maintain the resonators at a preset temperature in accordance with optimal environmental conditions for separating NVR from the sample fluid.

Abstract: A system and method that allows for early detection of biological conditions, such as a disease, through analysis of appropriate gaseous samples. The system and method are particularly amenable to the early screening for diseases, such as lung cancer, through the detection of specific biomarkers when present in exhaled breath from an individual. A preferred system implements a CO overtone laser that generates radiation and directs it through a photoacoustic cell. The absorption of the radiation is detected acoustically, and the absorption characteristics are utilized in determining the presence of a specific biological condition.

Abstract: A method and apparatus for determining chemical properties. The method is based on the sequential measurement of the variation of the oscillation frequency of a single sensing device when different chemically sensitive film materials are deposited on both sides of a resonator such as a quartz crystal microbalance (QCM). Each of the sides of the resonator is sequentially exposed to an analyte while another side is exposed to a blank gas. In this way, the analyte-dependent signal from the resonator is generated only from a single film. Measurements are further made by switching the analyte stream to expose the sensing film on another side of the resonator previously exposed to a blank.

Abstract: Provided is a process for measuring the amount of impurities in a gas sample filling a laser absorption spectroscopy analysis cell. The process includes calculating the value of a characteristic representative of the absorbance of the gas sample, from a measurement of the gas sample at a single given pressure, and quantifying the impurities on the basis of a predetermined law for the variation of the characteristic as a function of the amount of impurities. The characteristic is the ratio of the difference between the luminous intensity (Iana) of a light beam transmitted through the gas and the luminous intensity (Iref) of the incident beam to the luminous intensity (Iref) of the incident beam. The impurities are quantified on the basis of a value of the coefficient of proportionality between the amount of impurities and the characteristic, determined on the basis of a table of variation of the characteristic as a function of pressure, for a given amount of impurities.

Abstract: In a method of analyzing a concentration of a target substance contained in a fluid using a quartz oscillator having a surface covered with a layer capable of absorbing the target substance, the temperature of the fluid and the quartz oscillator is controlled at substantially the same predetermined temperature selected according to the concentration of the target substance in said fluid, so that the analysis can be made with optimum sensitivity. A device for analyzing a concentration of a target substance contained in a fluid, includes a contacting chamber accommodating a quartz oscillator, a temperature controller, disposed in a feed passage for feeding the fluid into said contacting chamber, for adjusting a temperature of the fluid at a desired predetermined temperature; and a detector of a frequency of the quartz oscillator.

Abstract: A method and apparatus for measuring properties of a fluid composition includes a mechanical resonator connected to a measurement circuit. The measurement circuit provides a variable frequency input signal to the mechanical resonator, causing the mechanical resonator to oscillate. To test the properties of a liquid composition, the mechanical resonator is placed inside a sample well containing a small amount of the fluid. The input signal is then sent to the mechanical resonator and swept over a selected frequency range. The mechanical resonator's response over the frequency range depends on various characteristics of the fluid being tested, such as the temperature, viscosity, and other physical properties. The invention is particularly suitable for combinatorial chemistry applications, which require rapid analysis of chemical properties for screening.

Abstract: A improvement for high precision ultrasonic chilled surface dew point hygrometry for measuring the density of condensation and the temperature at the same location on the surface of the sensor. The improvement for high precision ultrasonic chilled surface dew point hygrometry includes a piezoelectric substrate, and further having a conventional thermoelectric cooler connected thereto and a plurality of spaced heat sinks conventionally depending from the surface. Conventional acoustic devices are used to propagate surface acoustic waves and surface skimming bulk waves across the surface of the sensor. A series of the surface acoustic waves is used to measure the density of the condensation at a particular location on the surface of the sensor.

Abstract: The present invention is a photo-acoustic leak detection system that detects whether gas is leaking from a component. The system includes multiple beams wherein one beam is not absorbed by the gas and is used as a baseline measurement, while another beam absorbs the gas and emits an increased signal. Upon contact with the gas, an acoustic sensor senses the reaction or lack thereof between the gas and the beams, thereby allowing a signal processor to receive the respective alternating sensor signals after which the processor calculates the difference between the first and second signals to determine whether a leak exists. The photo-acoustic leak detection system also includes a beam combining means which forces the multiple beams to enter an acousto-optic cell at the same location. The acousto-optic cell, in turn, which is controlled by a signal controlling apparatus, sequentially and alternately diffracts the multiple beams at the same predetermined angle.

Abstract: In a sensor comprising a housing, through which a medium to be examined is conducted, the housing includes at least two passive building components capable of oscillating and oscillator circuits of which each includes an amplifier component and a variable phase shifting component providing for a phase shift range sufficiently large to switch the oscillating components off while the amplifier component remains operating.

Abstract: A sensor device for detecting the presence of a gas species in a gas environment susceptible to the presence of same. The sensor device may include a piezoelectric crystal coated with a sensor material having adsorptive affinity for the gas species, with an electric oscillator arranged for applying an oscillating electric field to the piezoelectric crystal to generate an output frequency therefrom indicative of the presence of the gas species when present in the gas environment, when the gas environment is exposed to the piezoelectric crystal. Another aspect of the invention involves a porous polymeric material that may be employed as a sensor material on a piezoelectric crystal sensor device, as well as a quartz microbalance holder that enables reactor gas monitoring. The sensor device alternatively may comprise an optical sensor arranged in a non-contaminating fashion in relation to the gas environment being monitored.

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.