Abstract: Apparatus and methods for detecting the presence of an airborne chemical or biological analyte utilize: a substantially gas- and liquid-impermeable container; means for introducing a substantially analyte-free collection liquid into said container; means for rapidly sampling ambient air and transferring said analyte therefrom into said collection liquid, said sampling means comprising an air intake means and and an air venting means; and means for removing from said container an analyte-enriched collection liquid; wherein said volume of air passes through a substantially horizontal air inlet and downward through a substantially vertical collector electrode tube with means for applying an electric field between said tube and a co-axial spiked wire- or rod-shaped discharge electrode.

Abstract: The present invention discloses a portable sampler for collecting an atmospheric sample. In one implementation, the portable sampler includes a portable housing with an interior portion; a sample inlet communicating between an area outside the housing and the interior portion of the housing; a sample cartridge in fluid communication with the sample inlet and adapted to store the atmospheric sample, the sample cartridge being removably secured within the housing; a pump disposed within the housing and in fluid communication with the sample inlet, the pump being arranged to draw the atmospheric sample from the area outside the housing into the sample cartridge through the sample inlet; and a carrier gas inlet communicating between the area outside the housing and the sample cartridge, the carrier gas inlet being configured to couple with a carrier gas source for sweeping the atmospheric sample from the sample cartridge into an analyzer while the sample cartridge is secured within the housing.

Abstract: Sensor module package having a housing element (3) with an opening (4) to a sensor cavity (6) for allowing outside air to reach a sensor device (1) positioned in the sensor cavity (6) for sensing a characteristic of the outside air. Sensor electronics (9) are connected to the sensor device (1) for providing an output signal. The sensor device (1) and sensor electronics (9) are positioned on a substrate (2). The sensor cavity (6) is formed by at least a cavity part of the substrate (2), at least a part of the housing element (3) and the opening (4). A cover member (11) is provided with a mechanical firming element (13) for mounting the sensor module package (10) in a vehicle.

Abstract: A gas detector and method of operating the gas detector that includes a carbon monoxide sensor and a processor. The carbon monoxide sensor senses an environmental concentration of carbon monoxide and provides the sensed value to the processor. Upon receiving the value of the carbon monoxide level (COppm), the processor determines an alarm threshold level based upon the COppm level. Once the alarm threshold level is determined, the processor calculates the COHb percentage for the current COppm reading based upon a derived, fixed point equation. The processor activates an audible/visual indicator when the sensed COHb percentage exceeds the alarm threshold.

Abstract: An environmental monitoring system and method is disclosed. The system includes one or more environmental measuring instruments, a controller in communication with the one or more environmental instruments, and a device located remotely from the controller capable of displaying data generated by the one or more environmental measuring instruments.

Abstract: A duct detector includes sampling tubes which slidably engage the detector with a fixed orientation to facilitate fluid flow. The tubes have a connector portion and a conduit portion. The connector portion and the conduit portion engage one another with a predetermined orientation.

Abstract: The present invention provides a device for continuous real-time monitoring of ambient air. The device includes a receptacle, a liquid supply, and a pressure balancing system. The receptacle includes a gas inlet slit located such that the gas inlet slit is covered by liquid within the receptacle during use. The pressure balancing portion of the present device includes communication between a point within the receptacle above the liquid level in the receptacle, as well as a liquid inlet portion at the lowermost end of the receptacle, and an air space above a liquid supply portion and the liquid supply portion itself, respectively.

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 method for the quantitative determination of atmospheric hydroperoxyl radical comprising: (a) contacting a liquid phase atmospheric sample with a chemiluminescent compound which luminesces on contact with hydroperoxyl radical; (b) determining luminescence intensity from the liquid phase atmospheric sample; and (c) comparing said luminescence intensity from the liquid phase atmospheric sample to a standard luminescence intensity for hydroperoxyl radical. An apparatus for automating the method is also included.

Abstract: A gas sensor assembly detects a constituent in a gaseous stream. The assembly comprises: (a) a mounting surface, (b) a sensor mounted on the mounting surface and sensor capable of generating a detectable signal in the presence of the constituent, and (c) an enclosing structure. The enclosing structure comprises: (i) a walled component having a pair of vertically spaced ends and mounted at one end on the mounting surface so as to circumscribe the sensor, and (ii) a gas-permeable membrane attached at the other end of the walled component, thereby defining an interior volume within said enclosing structure. Flowing the gaseous stream across the membrane infuses a portion of the gaseous stream into said interior volume containing the sensor.

Abstract: A flow-through monitor for detecting molecular contamination (MC) within a fluid flow. The monitor has a diffusion chamber having an inlet port and an outlet port, and a structure for supporting a fluid flow from the inlet port to the outlet port. The structure includes a flow gap causing a diffusion of molecular contaminants into the diffusion chamber, while substantially preventing, for a rate of the fluid flow above a predetermined magnitude, particulate contaminants within the fluid from entering the diffusion chamber. A SAW device detects molecular contamination interior to the diffusion chamber. Fluid input to the flow-through monitor may be diluted by a pure fluid for extended monitor life. A system for aggregate sampling connects an ensemble manifold upstream of the flow-through monitor. A system for triggered sampling connects a sample preconcentrator downstream of the flow-through monitor. A chemically selective membrane may be located between the flow gap and the SAW.

Abstract: Screening of items for the presence of contaminants, such as explosives residue, is accomplished by subjecting an item loaded into a pressure chamber to a pressure substantially in excess of atmospheric pressure conditions and rapidly decompressing the item to the ambient atmospheric pressure. The rapid decompression serves to scavenge vapors and particles from the exterior and interior of the item and any objects it contains. A sample of the vapors and particles removed from the item by the rapid decompression is sampled and is tested to determine whether a predetermined contaminant is present in the sample. Depending on the types of contaminants for which the sample is tested, it is possible to detect whether explosives, biological or chemical agents, and/or narcotics residues are present on or in the item being screened.

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: The invention disclosed herein relates generally to mailpieces and more particularly, a hazardous material detector for detecting hazardous material in a mail stream. The present invention is directed, in general to detector for collecting sample (s) of hazardous materials from a mail processing device. The mailpiece generally comprises an envelope comprising a front side and a back side; holes formed in at least one of the front side or the back side of the envelope; a hazardous material test strip for detecting the presence of hazardous material in contact with the test strip; whereby when hazardous materials are detected by the hazardous material test strip a physical change occurs to the hazardous material test strip and the physical change can be viewed through at least one hole formed in the at least one of the front side or the back side of the envelope. The detector helps to quickly determine whether hazardous materials are present in the mail stream.

Abstract: Systems, methods and apparatus for detecting concealed security threats by sampling molecules of substances for assessment wherein these molecules may be contained in the air in or near concealed security threats. Inspection of cargo containers by sampling the air contained therein and then analyzing the sampled air from the container for security threats including chemical, biological, radiological, nuclear, and high-explosive threats without requiring the modification of the existing container, the movement of the container to a particular inspection site, and without opening the container. Nuclear security threats may also be scanned for with close proximity nuclear radiation detection sensors closely coupled to areas at or near the concealed security threats. In addition, detection of other types of contraband, including illegal substances, embargoed materials and human and/or animal stowaways may also be assessed.

Abstract: Systems and methods for the detection of substances (particularly particulate substances) within mail pieces, specifically letters and other “flats” of mail. In particular, the systems and methods are for the detection of residues of Chemical or Biological Warfare Agents (CBWAs) which may be present within the mail pieces. The system is principally designed to be included as part of Dual Pass Rough Cull System (DPRCS) for the collection and detection of the residue when the contaminated mail piece first enters a mail facility and before it is intermingled with other mail pieces. The system also utilizes aerosol chambers using at least two arrays of pinch rollers to provide for decreased incremental changes on mail pieces and decrease the likelihood of mail piece damage.

Abstract: Systems and methods for the detection of substances (particularly particulate substances) within mail pieces, specifically letters and other “flats” of mail. In particular, the systems and methods are for the detection of residues of Chemical or Biological Warfare Agents (CBWAs) which may be present within the mail pieces. The system is principally designed to be included as part of Dual Pass Rough Cull System (DPRCS) for the collection and detection of the residue when the contaminated mail piece first enters a mail facility and before it is intermingled with other mail pieces.

Abstract: A gas detector having an intake to let in the gas to be detected and detecting the gas let in through the intake by a gas sensor, in which a porous film is horizontally arranged over the gas intake, in order to prevent the gas permeability of the porous film from being affected by water, oil and/or dust riding on the porous film, wherein a water-repellant and oil-repellant porous film is horizontally provided in a stretched state over the upper end of the intake, and the outside of the outer circumferential edge of the porous film is so structured as to allow liquid on the porous film to fall externally.

Abstract: A method and system for automated remote microbial air sampling includes a sampling enclosure positioned outside an isolator. An infeed sample receiver passes sample containers into the enclosure. An atrium is located within the enclosure and exposes containers to a gas sample. A remote sampling device collects the gas sample from the isolator and passes it to the atrium. A load arm is located within the enclosure. The load arm intermittently permits containers to enter the enclosure and moves containers to the atrium. An outfeed sample receiver passes containers out of the enclosure. The system allows addition and removal of containers from the air sampling system without interrupting the processing of the containers within the enclosure, and allows the first container supplied to the air sampling system to be the first exposed container removed therefrom.

Abstract: The present invention refers to a method of detecting the moisture in an apparatus for treating and preparing food, as well as to a method of treating and preparing food. In the method according to the invention, the current temperature values and speed values of the asynchronous motor driving a gas supply and circulation mechanism are compared to at least one characteristic line which is stored in a computer, and the current moisture in the gas mixture is determined from the deviation ?N of the measured speed from the speed of the stored characteristic line. The present invention also comprises an apparatus for treating and preparing food that, in particular, serves to carry out the method of determining the moisture in a gas mixture.

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 carbon monoxide (CO) detection unit incorporates a sensor which is a film or layer of NixCo1-xOy where x is from 0.1 to 0.9, e.g., spinel. The CO is detected by measuring the change in the electrical properties of the sensor. The detector can measure CO concentrations below 100 ppm and is capable of operating at room temperature and can be applied to domestic, industrial, medical and vehicular use.

Abstract: Screening of items for the presence of contaminants, such as explosives residue, is accomplished by subjecting an item loaded into a pressure chamber to a pressure substantially in excess of atmospheric pressure conditions and rapidly decompressing the item to the ambient atmospheric pressure. The rapid decompression serves to scavenge vapors and particles from the exterior and interior of the item and any objects it contains. A sample of the vapors and particles removed from the item by the rapid decompression is sampled and is tested to determine whether a predetermined contaminant is present in the sample. Depending on the types of contaminants for which the sample is tested, it is possible to detect whether explosives, biological or chemical agents, and/or narcotics residues are present on or in the item being screened.

Abstract: A diffusion status prediction method and system for a diffused substance are disclosed. The diffused substance is replaced by particles, and positions which the particles generated from an emission source arrive at are found by computation. The arrival positions and a post-emission elapsed time are recorded in association with each other. Also, intensity data showing the intensities of the particles during the passage of the post-emission elapsed time are set. Then, the intensity of the particles at the point in time at which the particles were generated is found by reference to the intensity data based on the post-emission elapsed time. For each particle, the arrival position, the post-emission elapsed time, and the intensity are recorded in association with each other. The concentration of the diffused substance in a predetermined area after a lapse of a predetermined time can be determined by adding up the intensities of the particles present in the predetermined area.

Abstract: A photoionization detector comprising multiple ionization cells for detecting the presence of chemical compounds in multiple fluid samples. The photoionization detector uses a single source of ultraviolet (UV) radiation to emit high energy photons into at least two ionization cells. Each ionization cell comprises at least one fluid inlet and at least one fluid outlet. Independent samples of fluid can be introduced into each cell and exposed to the UV radiation such that any molecules with an ionization energy lower that the energy of the photons are ionized. Each ionization cell also comprises a set of at least two electrodes arranged to generate an electric field such that ionized molecules are attracted to the electrode at lower voltage potential resulting in an electrical current.

Abstract: The invention relates to a method for operating a circuit arrangement containing a microcontroller (10) and an EEP-ROM (11). A first memory area (39) having at least one data set memory (DA1, DA2, DA3) and at least one second memory area (30) also having at least one data set memory (DB1, DB2, DB3) are provided in the EEPROM (11). A pointer (P1, P2, P3) located in a third memory area (31) refers to the respectively valid memory area (29, 30). In one step (53), the microcontroller (10) stores a data set in the invalid memory area (29, 30) and, in a subsequent step (54), changes the pointer (P1, P2, P3) so that the invalid memory area (29, 30) becomes the valid memory area (30, 29). Both steps (53, 54) are cyclically repeated. In the event of a fault during a storage process, a correct data set is available at all times in the memory area (29, 30) indicated as being valid.

Abstract: Device, in particular for use in a motor vehicle, having a sensor arrangement (21), which controls an air-conditioning unit, for determining the ambient-air quality, and an arrangement of ozone sensors (21, 22) upstream and downstream of a radiator (1), in particular of the motor vehicle, which is coated with a catalyst material for detecting the conversion rate of the conversion of ozone into oxygen which is effected by the catalyst.

Abstract: A semiconductor gas sensor, for example for measuring CO, NOx, O3, etc., exhibits a heatable sensor element for measuring gas concentrations, and a housing in whose interior the sensor element is disposed. The housing has a first opening, which connects the interior to the exterior. The housing has one or more second openings, which lie deeper than the first opening so that a gas stream is driven by means of convection from the second opening to the first opening. The semiconductor gas sensor can be made of silicon by means of micro engineering.

Abstract: A method and apparatus for monitoring air quality is provided.

Abstract: A lightweight, economical, mass-producible, reusable airfoil can be deployed in an airspace while in or attached to any moving vehicle for the purpose of collecting air samples. A frame has an airfoil shape that provides pressure differentials that preferentially direct particulates and contaminants of differing size and mass to different areas of an absorbent media attached or integral to the frame. The absorbent media are readily detachable from the frame for sanitary and efficient transfer to facilities where the samples can be analyzed.

Abstract: Method for checking the conversion capacity of a catalytic element for converting ozone where the catalytic element is provided as a vehicle radiator with a catalytic coating and the method of checking uses ozone sensors upstream and downstream of the radiator. The check is only carried out if predetermined enable conditions are satisfied. Only then are the values emitted by the sensors recorded and compared with one another. A variable which represents an uncorrected value for the quality of the conversion capacity is derived from this comparison. This variable is weighted as a function of at least one operating parameter of the vehicle. The weighted variable is compared with a predetermined threshold value, and, if the threshold value is exceeded, it is concluded that the conversion capacity of the radiator is insufficient.

Abstract: An asynchronous motor is used in the process for determining the proportion of a gas constituent, especially water vapor, contained in a gas mixture. The asynchronous motor drives a delivery device for circulating the gas mixture that is used for treating foodstuffs. The difference between the rotational speed, which occurs while the delivery device is driven, and the synchronous rotational speed, i.e. the slip, is used as a measure for the sought proportion of the gas constituent at respectively established pressure and temperature values of the gas mixture.

Abstract: An air-sampling carrier for sampling air from a clean room of a semiconductor processing facility, an apparatus and a method for analyzing the air, wherein the air-sampling carrier includes a container having an inner space, a door mounted at a front wall of the container, a discharging pipe for discharging the air sample out of the container, and at least one inlet tube for introducing purge gas into the inner space of the container from outside the container. The discharging pipe and inlet tube are respectively formed on an outer surface of the container and connected to an inner space of the container. The air in the unit process tools is effectively sampled using an unmanned carrying apparatus and the pollution level of the air sample is simply and easily measured.

Abstract: The present invention is related to the sensing of analytes and in particular, to methods of determining, resolving, identifying, or quantitating such analytes once detected. This invention provides systems and methods for identifying analytes, comprising using an importance index to give greater weight to the responses from sensors that measure characteristics most useful for identification of analytes. In other aspects, the systems and methods are useful for increasing the stability of electronic nose systems by prolonging the predictive capability of the training set of known analytes. In still other aspects, the systems and methods are useful for detecting and responding to events correlated with the presence of an analyte.

Abstract: A pressure sensor comprising a stable polymer having a backbone containing nitrogen and one or more of sulfur or phosphorous, and including a phosphorescent dye agent.

Abstract: An air-sampling carrier for sampling air from a clean room of a semiconductor processing facility, an apparatus and a method for analyzing the air, wherein the air-sampling carrier includes a container having an inner space, a door mounted at a front wall of the container, a discharging pipe for discharging the air sample out of the container, and at least one inlet tube for introducing purge gas into the inner space of the container from outside the container. The discharging pipe and inlet tube are respectively formed on an outer surface of the container and connected to an inner space of the container. The air in the unit process tools is effectively sampled using an unmanned carrying apparatus and the pollution level of the air sample is simply and easily measured.

Abstract: An air monitoring system is disclosed having an air monitoring unit with at least one sensor for measuring data of an air quality parameter and a computer for storing the air quality parameter data received from the sensor. The air monitoring unit may use an installed or a portable system, or a combination of both, for measuring the air quality parameters of interest. A remote data center may be provided, and the data may be uploaded to the data center from the unit by a communications media such as the Internet. Information or instructions may also be downloaded from the data center to the unit via the communications media for controlling or modifying the function of the unit. An expert system may be provided with the air monitoring system for controlling the unit. The information or instructions downloaded to the unit may be generated by the expert system.

Abstract: The invention is directed to a method for measuring gas concentrations with a measuring head which is provided with a satellite-supported global positioning device. With the method, gas concentrations at various locations can be determined. The position of the measuring head is determined at predetermined time intervals and first position data of a previously measured first position is compared to second position data of a current position. When a predetermined limit value between the first position data and the second position data is exceeded; a measured value of gas concentration corresponding to the current position together with the second position data are stored in a data memory of the measuring head.

Abstract: Changes in the concentration of a chemical, such as a gas, are determined using a non-linear chemical sensor which is subject to shifts in calibration over time. In order to minimize errors caused by such shifts in calibration a first infrared signal (Ig(1)) is measured and using an absorption value under an assumed chemical concentration (C(1)), a zero chemical signal Io(1) is calculated using the known physical law and mathematical relation Absorption=1−Ig/Io. A second infrared signal (Ig(2)) is then measured and the absorption value is calculated using the previously calculated zero chemical signal. A second concentration (C(2)) is then determined and the change in concentration is calculated by subtracting C(2) from C(1).

Abstract: A method for indicating a condition of oxygen depletion in a space, is disclosed. The method of measuring oxygen depletion is employed using the rate of change of carbon dioxide as a surrogate indicator of the amount of oxygen being depleted or displaced in the air. Displacement may be measured when the rate of change of carbon dioxide concentration falls within a rate of change range, or rises above or falls below a rate of change threshold level that indicates the displacement of oxygen.

Abstract: A desiccant pack 1 with a humidity sensor comprises a pack body 10 formed by sealing the three opened sides of a package film having gas permeability and heat sealability, and a desiccant is filled inside the pack body 10. Humidity sensor substances are applied in a band or strip-shape to the surface of the pack body 10, by which humidity sensors 21, 22 and 23 are applied directly to the pack.

Abstract: The present invention relates to a quantitative measuring method of argon impurity contained in high purity oxygen by means of triple point and &ggr;-&bgr; phase transition of oxygen, and also to a cryostat employed in quantitative measuring of argon impurity contained in high purity oxygen.

Abstract: Apparatus is provided for sampling gas in operative association with a combustion appliance, such as a furnace. The combustion appliance includes a first conduit through which combustion air is supplied to the appliance and a second conduit through which gas heated by the appliance is discharged from the appliance. The sampling apparatus includes a third conduit communicating between the first and second conduits and a gas sensor operable to sense a selected gas in the heated gas present in the third conduit. Operation of the appliance creates a pressure difference between the first and second conduits to draw a sample of heated gas from the second conduit into the third conduit, so that no mechanical device, such as a pump, is needed to transport the sample of heated gas to the gas sensor. A temperature sensor is provided for sensing temperature of the gas in the third conduit to verify gas flow in the third conduit.

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 portable medical gas system tester is small, lightweight, sturdy, self-contained and portable and can be either pen-activated and/or voice-activated so that it can be operated in the field by just one person. The device can test, collect and interpret data from all medical gas components, such as outlets, valves, alarms, central sources of supply and emergency low pressure oxygen fill connections, and with all medical gases including oxygen, air, vacuum, waste anesthetic gas disposal, nitrous oxide, nitrogen, carbon dioxide and carbon dioxide/oxygen mixtures. The device has a computer, a digital display device, an analog to digital converter, a gas sensor, a pressure and vacuum transducer coupled to the gas sensor, and an oxygen transducer coupled to the gas sensor, an exhaust outlet for venting excess gases to outside of the device's case, a bi-directional flow sensor coupled to gas sensor, and a flow transducer coupled to the flow sensor.

Abstract: A humidity sensor which utilizes microwave energy to determine a particular humidity value, e.g., a relative humidity, a specific humidity, or a dew point, without the need for delicate moving parts. The microwave humidity sensor requires little if any maintenance over a significantly long operational life, and is capable of highly accurate humidity measurements even at the extremes (e.g., toward 0% relative humidity and toward 100% relative humidity. In the disclosed embodiment, a microwave generator/transmitter is continuously or periodically pulsed to cause a known amount of microwave energy to be propelled through a metal tube structure, e.g., a waveguide tube structure. A microwave detector measures the amount of microwave energy at the other end of the tube structure.

Abstract: An acoustic wave based-chemical sensor containing a crystal substrate and a coating of small particulate matter is disclosed. The small particulate matter can be graphite particles. 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 coating absorbs the analyte, thus changing the mass of the sensor, and accordingly changing its resonant frequency. The transducers detect this change in resonant frequency to indicate that the analyte is present. The use of small particulate matter results in a coating having a large surface area which facilitates mass uptake of large amounts of VOCs, improved acoustic properties even with relatively thick coatings, and a high operational temperature range.

Abstract: A system and method are set forth for photoacoustical analysis of isotope and other compounds having telltale absorption wavelengths between 1700-2500 nm. The system and method includes a Co:Mg F2, an optical parametric oscillator (OPO), or a diode laser tunable between 1700-2500 nm which is directed into a sample at energies sufficient to generate detectable acoustical emissions. A microphone detects the emissions for processing and analysis. The system and method is adapted to detect stable isotope compounds such as 13CO2 as well as other chemical compounds. For non-gaseous compounds, a CO2 or diode laser is used to photoablate the gaseous sample containing the suspected compound.