Abstract: Various example embodiments described herein relate to a sensor assembly. The sensor assembly includes a first sensor cover and a second sensor cover. The first sensor cover is disposed on a first end of the sensor assembly and the second sensor cover is disposed on a second end of the sensor assembly. The first sensor cover defines a first capillary and the second sensor cover defines a second capillary therethrough. The sensor assembly further includes a first sensing unit, a second sensing unit, and a filter. The first sensing unit and the second sensing unit are disposed between the first sensor cover and the second sensor cover. In some example embodiments, the filter is reactive to a target gas and thereby prevents an inflow of the target gas through the second capillary into the sensor assembly.

Abstract: Various embodiments described herein relate to methods, apparatuses, and systems for recovering gas sensors from silicone poisoning. In an example embodiment, a method of recovering a gas sensing apparatus from silicone poisoning is provided. The method includes exposing the gas sensing apparatus to a predetermined hydrogen concentration for a period of hydrogen exposure time. The predetermined hydrogen concentration breaks down the silicon oxide bonds formed on a catalytic bead of the gas sensing apparatus. The method also includes providing a methane concentration to the gas sensing apparatus for a period of methane exposure time. The method further includes determining that the gas sensing apparatus satisfies a predetermined calibration sensitivity based on the reaction of the gas sensing apparatus to the methane concentration.

Abstract: A calibration device and method of manufacturing the same. The calibration device for a hearing earpiece configured to at least partially protrude into the ear canal of a user includes a calibration base. The calibration base a calibration insert. An air chamber is defined between the calibration base and the calibration insert. The calibration device also includes at least one earpiece receiving mechanism defined on the calibration insert. The at least one earpiece receiving mechanism is configured to create an sealed connection between given ear piece and the air chamber for calibration. The earpiece receiving mechanism is configured to at least partially receive the given earpiece. A corresponding method of manufacturing is also included.

Abstract: An integrated sensor of volatile organic gas can include a photoionization detector (PID) and one or more additional detectors such as an infrared detector, a catalytic combustion detector, or an electrochemical detector. One embodiment includes a methane detector that allows correction of the PID measurements for the interference of methane with the PID and/or allows a combination of measurements of the sensors to measure a total hydrocarbon concentration. A further sensor of non-hydrocarbon quenching gases such as carbon dioxide may also be used in correction of the PID measurements.

Abstract: A radiation detector can perform both rate and dose measurements for personal safety and also to provide measurements that are sufficiently sensitive for security applications. In one embodiment, a radiation detector has a first measurement channel and a second measurement channel, where the second measurement channel can measure radiation at levels that would saturate the first measurement channel. The detector can automatically switch between the high and low sensitivity channels while continuously integrating the measured rates to determine a radiation dose. The detector can also conserve power by automatically shutting off the unused measurement channel and still give a personal safety warning when the radiation rate or the dose reaches respective alarm thresholds.

Abstract: An oxygen sensor includes a solid polymer electrolyte, e.g., on an acid treated Nafion membrane and uses a diffusion-limited fuel cell type reactions. The sensor avoids electrolyte leakage and avoids consumption of electrodes. In different configurations, a counter or reference electrode can be on the same or the opposite side of the electrolyte as a sensing electrode. An insert limits and controls oxygen diffusion into a sensing chamber containing the sensing electrode that catalyzes reduction of oxygen. Applying appropriate bias voltages to the reference and sensing electrodes causes an output current of the sensing electrode to be proportional to the rate of oxygen consumption based on Frick's law under a diffusion-limited mode. The output current can be measured, e.g., using a resistor to convert the current to a voltage signal.

Abstract: A photo-ionization detector having an adjustable drive power for a UV lamp implements a calibration operation that determines measurement signals for a series of drive power levels and based on the resulting measurement signals selects one or more drive power levels for normal operation of the PID. The calibration operation permits use of UV lamps having a wider range of performance levels and thereby improves manufacturing yields and extends the useful life of the PID. During normal operation, the PID further fine-tunes the drive power level to compensate for expected or measured degradation in lamp performance. Accordingly, between calibrations, the PID maintains a more uniform UV intensity for more accurate measurements. To expand the measurement range of the PID, the calibration process can select two or more power levels for use when measuring different gas concentrations.

Abstract: A photo-ionization detector (PID) including two detection units controls gas flows through the ionization chambers of the detection units for real-time self-cleaning and measurement. Operation of the PID can include flowing gas through the ionization chamber of one detection unit to measure the volatile gas concentration while stopping gas flow through the ionization chamber of the other detection unit. A UV lamp converts oxygen contained in the closed ionization chamber to ozone, which removes contamination in the closed ionization chamber, Continuous gas flows can alternate between one ionization chamber to the other. Alternatively, a PID with only one gas detection unit intermittently interrupts the flow of the ambient gas in the ionization chamber.

Abstract: A gas analysis system and method use foreground broadband gas monitoring and background selective gas analysis. The foreground broadband monitoring indicates concentrations of a class of chemicals or contaminants in a gas sample, provides real-time warnings of contaminants, and can activate the background selective analysis. Separate broadband detectors and gas analyzers can respectively perform broadband monitoring and selective analysis. To reduce system components, a broadband detector that performs broadband monitoring switches to measure concentrations of chemicals output from a separation device for the selective analysis.

Abstract: A photo-ionization detector (PID) employs combinations of ion mobility spectrometry, ionization energy discrimination, and chemical filtering to identify the presence and quantity of specific gases. One such PID introduces a gas sample into an ionization chamber at an end of a drift tube. UV light from a PI source ionizes ionizable molecules contained in the gas sample. The PI source includes either multiple UV lamps, each having a specific energy level for discriminating between potential constituents of the gas sample or one multiple-energy level UV lamp with different light bandwidth window zones and a zone selector. A shutter grid separates the ionization chamber from the drift tube. When the shutter grid is open, an electric field in the drift tube attracts ions that travel against the flow of a drift gas until a collector electrode at the end of the drift tube captures the ions. A time required for the ions to travel the length of the drift tube is characteristic of the type of ion.

Abstract: An NDIR sensor includes a cylindrical metallic tube, a printed circuit board platform that fits into one end of the tube, a diffusion filter that fits into the opposite end of the tube, and an optical system. The optical system includes an infrared source on the platform, a mirror on the inner wall of the tube so as to reflect and focus the infrared light from the infrared source, and a detector assembly that receives the infrared light after reflection. The gas sensor may further include a partition between the infrared source and the detector assembly, a removable filter on the diffusion filter, connecting pins attached to the platform, and a sealing layer formed under the platform. The detector assembly includes a signal detector and a reference detector. A first and second bandpass filters are respectively formed on the signal and reference detectors.

Abstract: A discharge ionization detector (DID) includes a sensor that uses an alternating current (AC) discharge through a working gas as an ionization source. The sensor includes a discharge chamber, into which the working gas is introduced, and an ionization chamber, into which a sample gas is introduced. UV photons from the discharge chamber and metastable particles that enter the ionization chamber from the discharge chamber ionize molecules in the sample gas. The ions generated from the ionized sample gas are measured as a current indicating the quantity of ionizable molecules in the sample gas. For selective identification of molecules in the sample gas, one or more chemical filters can filter the sample gas to separate target gases from gases that interfere with detection of the target gases. Additionally, a supply for the working gas can change the working gas to change the maximum energy available for ionization of the sample gas.

Abstract: A multiple-channel photo-ionization detector (PID) determines the concentrations of specific gases or classes of gases. The PID includes a UV lamp, an optical window which is divided into multiple zones with each zone producing a UV light beam having a distinctive maximum photon energy. The ionization chamber of the PID includes multiple ion detectors. The PID measures ionization currents and concentrations of gases ionizable by each UV light beam. A method of determining the concentrations and/or identifications of the individual component gases uses differences and/or ratios of measured concentrations or currents.

Abstract: A dual-channel photo-ionization detector (PID) and a method for calculating the gas concentration in the PID are disclosed. The PID includes a UV light source which produces a UV light to ionize a gas, first and second identical ion detectors for measuring first and second currents including ion, and a UV shield which differentially shields the ion detectors from the UV light. The differential shielding of the ion detectors enables the PID to differentiate between current caused by ions and current caused by the photoelectric effect of the UV light. The detector measures a concentration of the gas irrespective of a variation of an intensity of the UV light. A heater in the PID stabilizes the temperature for measurements and prevents condensation in the PID.

Abstract: A photo-ionization detector (PID) includes an ultraviolet (UV) lamp that transmits UV light into an ionization chamber to ionize volatile gases. An ion detector in the ionization chamber includes interdigital electrodes that collect resulting ions using an electrical field perpendicular to the UV light propagation. A pump in the PID circulates gases through the ionization chamber in a direction perpendicular to the electrical field and to the UV light propagation. The PID additionally provides a UV monitor having interdigital electrodes that release electrons when struck by the UV light. The size of a monitor current in the UV monitor indicates the intensity of the UV light. The UV monitor is in a UV monitor chamber that protects the UV monitor from exposure to the ionized gases and improves the accuracy of UV intensity measurements.

Abstract: A photo-ionization detector (PID) which measures volatile organic gas uses electrically insulated parallel plates to energize a miniaturized gas discharge UV lamp and an energy efficient method to modulate the UV lamp intensity and reduce power consumption. A miniaturized centrifugal pump is integrated into the PID to provide active sampling for fast response to volatile gas. An ionization chamber in the PID includes a UV shield which protects a measurement electrode from UV light and a UV monitor which measures changes in UV intensity due to external interferences and UV lamp variations. A microprocessor in the PID uses measurements from the measurement electrode and from the UV monitor to accurately account for UV intensity variations when determining a volatile gas concentration.

Abstract: A photo-ionization detector utilizes an ultraviolet (UV) lamp and is designed for detecting and measuring the concentration of volatile gases flowing between closely spaced parallel electrodes. One of the electrodes is formed to allow photons to pass into the space between the electrodes to ionize the volatile gases between the electrodes. The detector also incorporates an improved ionization chamber.

Abstract: A photo-ionization detector utilizes an ultraviolet (UV) lamp for detecting and measuring the concentration of volatile gases flowing between closely spaced parallel electrodes. One of the electrodes is made of mesh to allow photons to pass into the space between the electrodes to ionize the volatile gases between the electrodes. The detector also incorporates an improved ionization chamber. In other embodiments, a plurality of gas discharge lamps, each generating a different photon energy, may be placed adjacent to a plurality of closely spaced electrodes, all electrodes in one ionization chamber, to detect and measure different types of volatile gases that may exist.