Abstract: An NDIR gas sensor is housed within a mechanical housing made up of a header housing, a can mounted to the header housing, and a sample chamber mounted above the can. The can has a top surface with a pair of windows formed in it to allow radiation to enter and return from the sample chamber. An electronics module is mounted on a printed circuit board hermetically sealed within the can. A signal channel path length detected by the signal detector is greater than a reference channel path length detected by the reference detector and an absorption bias between the signal and reference outputs can be used to determine a gas concentration in the sample chamber. Both the signal detector and the reference detector have an identical narrow band pass filter with the same Center Wavelength (“CWL”), Full Width Half Maximum (FWHM) and transmittance efficiency at the CWL.

Abstract: An NDIR gas sensor is housed within a mechanical housing made up of a header housing, a can mounted to the header housing, and a sample chamber mounted above the can. The can has a top surface with a pair of windows formed in it to allow radiation to enter and return from the sample chamber. An electronics module is mounted on a printed circuit board hermetically sealed within the can. A signal channel path length detected by the signal detector is greater than a reference channel path length detected by the reference detector and an absorption bias between the signal and reference outputs can be used to determine a gas concentration in the sample chamber. Both the signal detector and the reference detector have an identical narrow band pass filter with the same Center Wavelength (“CWL”), Full Width Half Maximum (FWHM) and transmittance efficiency at the CWL.

Abstract: The construct of a specially designed air sampler and its function in order to carry out the Effortless Recalibration (ERB) procedure to an Absorption Biased (AB) designed NDIR gas sensor with the use of a Calibration Master is described.

Abstract: Two detectors of the same kind, each having an identical neutral band-pass filter to the target gas, are installed next to Signal channel and Reference channel detectors as pairs in an AB designed NDIR gas sensor layout, which are called Standard Signal channel detector and Standard Reference channel detector. “Standard” GAMMA is the ratio of Standard signal channel detector output over that of Standard Reference channel detector. “Standard” GAMMA is independent of the measurement Physics of NDIR gas sensors, is dependent only upon the performance characteristics of the sensor component and is also independent of the presence of any amount of target gas in the sample chamber. Consequently, “Standard” GAMMA can be used to proportionally correct and update GAMMA of the sensor as its components age over time thereby rendering such an AB designed NDIR gas sensor self-commissioning or staying accurate over time after initial calibration.

Abstract: An NDIR gas sensor takes advantage of a conventional packaging embodiment commonly used to house detectors of all kinds comprising a can, header and a dish sample chamber all welded together to form a single detector unit. The can forms the top, a hollowed out header body forms the middle and a custom dish sample chamber forms the bottom of a completely functioning NDIR gas sensor. Whereas the header body not only accommodates all the optoelectronic and optical parts on its top surface providing the required signal processing functions for the gas sensor, part of its body is excavated below to accommodate a custom dish sample chamber in communication with the gas outside whose concentration level is to be measured. A lens and windows are also fabricated on the top part of this header body so that infrared radiation can enter the dish sample chamber below and then be redirected back above for signal processing.

Abstract: An NDIR gas sensor takes advantage of a conventional packaging embodiment commonly used to house detectors of all kinds comprising a can, header and a dish sample chamber all welded together to form a single detector unit. The can forms the top, a hollowed out header body forms the middle and a custom dish sample chamber forms the bottom of a completely functioning NDIR gas sensor. Whereas the header body not only accommodates all the optoelectronic and optical parts on its top surface providing the required signal processing functions for the gas sensor, part of its body is excavated below to accommodate a custom dish sample chamber in communication with the gas outside whose concentration level is to be measured. A lens and windows are also fabricated on the top part of this header body so that infrared radiation can enter the dish sample chamber below and then be redirected back above for signal processing.

Abstract: Two detector elements are optically isolated by having them mounted (die-attached) on the same header so that the thermal tracking of the detectors respectively for the signal and reference channels is close to ideal. Furthermore, such an optical isolation technique or cross-interference suppression between the two detector elements mounted on the same header also allows the use of only one and the same narrow band pass interference filter covering both detectors. Thus the thermal tracking of the filters respectively for the signal and reference channels is also close to perfection as both channels share the same filter.

Abstract: A fire detector and method of using it generate a fire alarm through use of a smoke detector and a carbon monoxide detector once the smoke detector detects a threshold level of light obscuration for greater than a first pre-selected time period or a reduced threshold level of light obscuration for greater than a second pre-selected time period or the CO detector detects a rate of increase in CO concentration which exceeds a first preselected CO rate for a third pre-selected time period and the smoke detector detects the reduced threshold level of light obscuration or the rate of increase in CO concentration exceeds a second preselected CO rate for a fourth pre-selected time period.

Abstract: Two detector elements are optically isolated by having them mounted (die-attached) on the same header so that the thermal tracking of the detectors respectively for the signal and reference channels is close to ideal. Furthermore, such an optical isolation technique or cross-interference suppression between the two detector elements mounted on the same header also allows the use of only one and the same narrow band pass interference filter covering both detectors. Thus the thermal tracking of the filters respectively for the signal and reference channels is also close to perfection as both channels share the same filter.

Abstract: NDIR gas sensing methodology is advanced which renders the output of an NDIR gas sensor, when implemented with this new methodology, to remain stable or drift-free over time. Furthermore, the output of such a sensor will also be independent of the temperature of an environ wherein the sensor is in physical contact. This method utilizes the same narrow band-pass spectral filter for the detection of the gas of interest for both the signal and the reference channels. By so doing, the two channels always receive radiation of the same spectral content from the infrared source of the sensor convoluted with that from any external elements exposed to the sensor. While the same sample chamber through which the gas of interest to be detected flows is shared by the two channels, the detector package for the reference channel is hermetically sealed with 100% of the gas to be detected instead of 100% N2 as for the signal detector.

Abstract: A nasal air filtration device includes a pair of either planar or concave-convex filters, a support structure incorporating a pair of generally annular bases or sleeves for supporting the filters, and a bridge that couples the bases or sleeves to maintain them in a desired spaced-apart relation and to determine a desired angular relationship. The support structure is insertable into the nasal cavities to position the filters within corresponding nasal cavities. Flexible rims maintain the support structure and the filters in spaced-apart relation to the surrounding nasal wall. The rims conform to surrounding nasal tissue to form seals. The rims can be selectively inclined to facilitate insertion and resist accidental removal. In certain embodiments the device is combined with a filter that covers the mouth to provide an air filtration system.

Abstract: An NDIR gas sensor and methodology use an absorption bias between signal and reference outputs to determine sample concentration of a gas being measured. The absorption bias is created by using a signal channel in a sample chamber with a signal path length that is greater than a reference path length of a reference channel in the sample chamber while both the signal and reference detectors have an identical narrow band pass filter with the same Center Wavelength (“CWL”), Full Width Half Maximum (FWHM) and transmittance efficiency at the CWL. Performance is improved when the reference detector and the signal detector share a common thermal platform that can also be shared by the sample chamber and the infrared source.

Abstract: The concentration of a gas species is detected by using a single beam NDIR gas sensor in which an infrared source element is driven at two different temperatures, a feed back loop senses an operation voltage of the source, a differential gain amplifier creates a high cycle amplified output during a high cycle and a low cycle amplified output during a low cycle while a controller synchronizes the source driver so that a signal processor can determine the gas concentration through use of the high cycle amplified output and the low cycle amplified output. The infrared source can be a non-genuine blackbody source such as an incandescent miniature light bulb when the sample chamber is a thermally insulated aluminum tube that is maintained at a preselected temperature greater than ambient so that the glass envelope of the bulb is maintained at an equilibrium temperature (such as approximately 30 degrees Celsius plus or minus two degrees Celsius) during its low cycle operation state.

Abstract: Concentrations of N gas species can be detected from a single beam NDIR gas sensor having a differential infrared source and an (N+1)-passband filter (having a neutral passband and N absorption passbands for N gases) mounted at a single infrared detector by driving the infrared source with N input power levels to render the source into emitting at N distinct temperatures whose radiation outputs are characterized by N corresponding Planck curves which are dependent only upon the respective source temperatures and which link a Spectral Radiant Emittance MsubLamba with wavelength, measuring N detector outputs at the single infrared detector and detecting the concentrations of N different gas species, each of the N gas species having its own unique infrared absorption passband, by (a) setting up N causality relationship equations linking outputs of the detector respectively for N different source temperatures and a set of relevant parameters of the sensor components, (b) determining the values of all of the param

Abstract: A method for detecting the concentration of one or more gas species by using infrared radiation emitted from one or more sources into a sample cell which is a hollow waveguide with multiple bends collectively greater than 180 degrees in three dimensions, the infrared radiation being quasi-focused into a beam with an angle of incidence between greater than approximately 0° and approximately 10° relative to a longitudinal axis of a first linear segment of the sample cell proximate the source, then detecting two or more signals in which one of the signals is used to compensate for water vapor. The methods can detect gas concentrations down to 1 ppm or less.

Abstract: A fire detector and method for generating an alarm signal in response to a fire uses an NDIR CO2 sensor to generate a detector signal based upon a 15? absorption band of CO2 and generates an alarm signal when a signal processor receives the detector signal and a preselected criterion is met that is indicative of the onset of a fire based upon an analysis of the detector signal using a detection algorithm that relies upon a trending pattern of the detector signal such as recognizing a substantial drop in the detector signal strength. The NDIR CO2 sensor can also generate a reference detector signal based upon a 9.0? neutral band with a FWHM=0.5? while the signal processor utilizes a detection algorithm that is based upon a synchronized output signal representative of CO2 concentration to generate an alarm signal when a preselected criterion indicative of the onset of a fire is met.

Abstract: A fire detector with a passive CO2 sensor generates a detector signal based upon a 15? absorption band of CO2 and a signal processor generates an alarm signal when a preselected criterion is met. The passive CO2 sensor has a passive infrared source with a source temperature, a waveguide sample chamber with a gas medium temperature (which is less than the source temperature), a heat exchanger (that reduces the temperature of CO2 gas as it passes into the waveguide sample chamber and may be thermally coupled to the sample chamber) and an infrared detector assembly with a detector temperature (which is less than the source temperature). An exterior surface of the passive infrared source has a high emissivity while the detector assembly and the sample chamber (which can be thermally coupled to each other but not the passive infrared source) have a low emissivity.

Abstract: A fire detector and method for detecting fires uses a passive NDIR sensor that generates a detector signal based upon either a 15? absorption band of CO2 or a 6.27? absorption band of H2O and a signal processor which receives the detector signal and generates an alarm signal when a preselected criterion is met. The NDIR sensor relies upon a passive infrared source (such as a very thin film of black plastic material) with a high emissivity (e.g., approximately 1.0), a sample chamber with a low emissivity (e.g., approximately 0.03) thermally decoupled from the passive infrared source and an infrared detector located in a detector assembly thermally coupled to the sample chamber while a heat exchanger is thermally coupled to the sample chamber.