A novel evanescent-wave quartz-enhanced optical microfiber photoacoustic gas sensor is provided for detecting trace amounts of gas. Both fiber-taper based evanescent field and photoacoustic spectroscopy can be used to exploit the merits of both technologies. The use of a fiber half-taper into the tuning fork and microresonator tubes can result in reduced system size, simplified optical alignment, and high sensitivity. The techniques described can be used in chemical, biological and environmental sensing applications.

Composite films comprising an organic salt (or GUMBOS) such as 1-n-butyl-2,3-dimethylimidazolium hexafluorophosphate and a polymer such as cellulose acetate are prepared. These films are useful in detecting vapors of volatile organic compounds, and in determining their molecular weights. A quartz crystal microbalance-based sensor was designed by depositing a thin film of this composite material on the gold electrode surface of a quartz crystal resonator. The sensor exhibited rapid response toward a variety of volatile organic compounds, and complete regeneration, high sensitivity, low detection limits, and wide dynamic ranges. The ratio of the change in frequency to the change in motional resistance is a concentration-independent quantity that is proportional to the molecular weight of the absorbed chemical species. These properties facilitate the easy identification and molecular weight determination of a broad range of organic vapors.

A light emitter device contains a heater structure configured to emit light if a predefined current flows through the heater structure. The heater structure is arranged at a heater carrier structure. The light emitter device contains an upper portion of a cavity located vertically between the heater carrier structure and a cover structure. The light emitter device contains a lower portion of the cavity located vertically between the heater carrier structure and at least a portion of a carrier substrate. The heater carrier structure contains a plurality of holes connecting the upper portion of the cavity and the lower portion of the cavity. A pressure within the cavity is less than 100 mbar.

Various exemplary embodiments relate to a device to measure carbon dioxide (CO.sub.2) levels, including a first oscillator group comprising a first sensor to measure air pressure, where the first sensor comprises a first sealed membrane, and where the first sealed membrane overlays a sealed first cavity; a second oscillator group including a second sensor to measure the resonance frequency of a second unsealed oscillating membrane, and where the second unsealed membrane overlays a second cavity in contact with the air outside of the second sensor; and a mixer accepting as input a first frequency measurement output from the first oscillator group and a second frequency measurement output from the second oscillator group, outputting the difference of the first frequency measurement and the second frequency measurement, and computing a carbon dioxide measurement based on the difference.

Disclosed are methods for determining and classifying aircraft air contaminants comprising one or more of: turbine engine oil, hydraulic fluid and deicing fluid using contaminant analyzers comprising a contaminant collector comprising a membrane and a heater vaporizing the contaminants; a gravimetric sensor generating a response when contaminant mass is added to or removed from the sensor, the sensor receiving contaminants desorbed from the heated membrane; a frequency measurement device, measuring the response generated by the sensor as the contaminant is added to and removed from the sensor; a computer readable medium bearing a contaminant recognition program and calibration data; a processor executing the program, the program including a module classifying contaminants by type, and a module using the data for comparison with magnitude of response generated by the sensor to calculate contaminant concentration; and, a pump, generating flow of air through the collector before and after the membrane is heated.

A gas analyzer uses continuous sonic signals through a conduit to determine the composition of a gas in the conduit. A transmitting transducer drives sonic signals at a fixed frequency and a second transducer receives the sonic signals. The phase shift between two signals corresponds to the speed of sound through the gas and is related to the composition of the gas. The electronic versions of these signals are processed by lowering, or dividing, the fixed frequency which expands the range of phase shift measurement and allows the determination of an expanded range for the gas composition. In an ozone generation system, the gas analyzer is highly suitable for determining the composition of gases derived from air as a gas of known composition and a calibration point.

An odor measurement apparatus includes an odor sensor detecting an odor and an imaging device having a lens portion, in which an imaging direction of the imaging device and an introduction direction of air when the air is guided to a sensor surface of the odor sensor through an introduction port are substantially the same direction. The odor measurement apparatus detects odor substances contained in air using a sensor when an odor is measured, and measures attribute information of a measurement target or the like of the odor. An odor data management apparatus stores and manages odor data measured by the odor measurement apparatus.

A capacitive ultrasonic transducer includes a sensor head having a back plate, the structured front side of which is provided with an insulation layer, and the back side of which is provided with an electrode. In order to achieve an improved construction by means of which increased temperature resistance up to several hundred degrees Celsius can be achieved even in strongly oxidizing and reducing media, the membrane provided as a sound generator is subjected to tensile stress in a planar direction.

Disclosed is an integrated circuit comprising a substrate (10); and an optical CO.sub.2 sensor comprising: first and second light sensors (12, 12′) on said substrate, said second light sensor being spatially separated from the first light sensor; and a layer portion (14) including an organic compound comprising at least one amine or amidine functional group over the first light sensor; wherein said integrated circuit further comprises a signal processor (16) coupled to the first and second light sensor for determining a difference in the respective outputs of the first and second light sensor. An electronic device comprising such a sensor and a method of manufacturing such an IC are also disclosed.

An analytical system and method for detecting volatile organic chemicals in water including a coated SAW detector that provides for improved reduction of moisture at the coating of the SAW detector. A stabilized SAW sensitivity and long lasting calibration is achieved. The analytical system further includes an improved sample vessel and sparger that allow for easy grab sample analysis, while also providing efficient purging of the volatile organic compounds from the water sample. In addition, an improved preconcentrator provides a stabilized sorbent bed.