Abstract: Devices and methods are disclosed that are effective to produce reliable vapor measurements in the presence of drift. In certain instances the sensor module is mounted externally on a housing. In other instances, the sensor module contains a first sensor element incorporating a first array of sensors and a second sensor element incorporating a second array of sensors wherein both sensor elements are mounted externally on the housing. In other embodiments, the present invention relates to mapping an x-y surface for detection of an analyte, the method includes moving in tandem at least two sensor arrays separated by a distance “d” across an x-y surface to produce a plurality of responses and analyzing the responses to map the x-y surface for detection of an analyte. Moreover, the present invention provides a sensor module, such as in a handheld device, comprising at least two pneumatic vapor paths and at least two sensor arrays.

Abstract: Circuits include at least one-odor sensitive organic transistor having a conduction channel whose conductivity changes in response to certain odors. The organic transistors are interconnected to increase their response to selected odor signals. The organic transistors may be interconnected to form a ring oscillator whose frequency of oscillation changes in response to an odor signal and in which the alternating signal applied to the gate electrodes of the organic transistors enhances their recovery and reduces their drift.

Abstract: A gas sensor including an element 4 for measuring the concentration of a gas to be detected which is contained in a gas under measurement; a protector 2 provided to cover a tip end of the element 4 in the axial direction; and a protection cap 1 removably attached to the gas sensor. The protection cap 1 includes a tubular portion 106 which surrounds a side surface 202 of the protector 2, support portions 102 which project from an inner surface 161 of the tubular portion 106 and reach the side surface 202 of the protector 2 without axially partitioning the space between the inner surface 161 of the tubular portion 106 and the side surface 202 of the protector 2, and an air-outlet hole 103 for establishing communication between the interior and exterior of the protection cap 1.

Abstract: In a volumetric gas adsorption measuring method, an initial dead volume of the sample cell and an initial dead volume of a reference cell at the same time point are preliminarily determined. When the gas adsorption on the solid sample is to be measured, a change in the dead volume of the sample cell is calculated on the basis of an internal gas with the sample cell and reference cell immersed in a pressure of the reference cell measured at this time point cryogenic fluid temperature bath, the initial dead volume of the reference cell, and an initial gas pressure of the reference cell measured at a time point of the measurement of the initial dead volume of the reference cell. Then, the initial dead volume of the sample cell preliminarily measured is corrected on the basis of the change in the dead volume of the sample cell for the calculation of the amount of the gas adsorbed on the solid sample.

Abstract: A monitoring system, such as used to monitor the presence and/or concentration of gases or other such fluids, includes a housing through which fluid is permitted to pass and which includes a heater element. The housing includes one or more vent hole/vent plug combinations and fluid, including gas and/or liquid, passes through the vent hole/vent plug combinations to flow into, through and/or out of the housing. A heater element is located in the housing and maintains the housing interior above the dew point to facilitate proper operation of the sensor element. The heater element, in conjunction with the vent hole/vent plug combinations, facilitates a heated-air plume through the housing to avoid the build up of moisture therein and to expose the sensor element to a steady stream of ambient atmosphere for monitoring the gas concentrations in same.

Abstract: A gas analyzer for a semiconductor treater improved to be capable of monitoring leakage or change of gas composition influencing treatability of the semiconductor treater in situ is provided. A duct is provided on the outer wall of a chamber of the semiconductor treater for taking out gas to be analyzed from the chamber. A gas analytic chamber stores the gas to be analyzed taken out through the duct. A discharge formation part is mounted in the vicinity of the gas analytic chamber. The discharge formation part includes a high frequency generation coil generating a high frequency and forming a plasma of the gas to be analyzed in the gas analytic chamber. This gas analyzer further comprises a spectrometer analyzing the emission wavelength of the plasma of the gas to be analyzed.

Abstract: An electrochemical sensor element (10) for determining the oxygen concentration in exhaust gases of internal combustion engines is described. The sensor element (10) has a pump cell, which has a pump electrode (52) situated on a surface of the sensor element (10) facing the gas mixture, and a measuring gas electrode (50) situated in a measuring gas area (40), the gas mixture entering the measuring gas area (40) through a diffusion resistor (31). In addition, the sensor element (10) has a reference electrode (51) situated in a reference gas area (41). Another diffusion resistor (32) is provided between the measuring gas area (40) and the reference gas area (41).

Abstract: The mass of particulate matter in a particle laden gas stream is measured using a single mass detector. The particle laden gas stream and a substantially identical but particle-free gas stream alternately engage the mass detector during successive measurement time periods. A difference between a reading provided by the mass detector for a current measurement time period and a reading provided by the mass detector for a consecutive measurement time period is determined. This difference intrinsically corrects for volatilization losses occurring during the current measurement time period. A measure of the mass or concentration of particulate matter in the particulate laden gas stream is determined from this difference.

Abstract: A circuit includes at least one odor-sensitive organic field effect transistor (OFET) having a conduction channel whose conductivity changes in response to certain ambient odors and a feedback loop coupled between an output and an input of the circuit. The feedback loop generates a feedback signal which stabilizes the output signal of the circuit for time drift of the odor-sensitive organic transistor. In one embodiment, the OFET is an integral part of an amplifier and generates input signals to the amplifier in response to certain odors. A selectively enabled switch may be coupled between the output and the input of the amplifier circuit to provide negative feedback that tends to cancel the effect on the amplifier of time drift due to the OFET.

Abstract: A gas concentration measuring apparatus is provided which measures the concentration of two kinds of gas components such as O2 and NOx contained in exhaust gasses of an internal combustion engine of automotive vehicles. The apparatus has a gas sensor which includes a first cell responsive to application of a voltage to discharge O2 in the exhaust gasses to the outside and produce an electric current as a function of concentration of the discharged O2 and a second cell responsive to application of a voltage to produce an electric current as a function of concentration of NOx in the exhaust gasses from which the O2 is discharged by the first cell. The apparatus offsets an error component of the electric current produced by the second cell which depends upon O2 contained in the exhaust gasses.

Abstract: A detection device for an apparatus for carrying out analysis such as a chromatograph includes not only a detector for outputting detection signals but also a stabilization judging unit for measuring drift and noise of these detection signals over time and automatically transmitting a start signal which permits the apparatus for analysis to start its operations when the measured drift becomes smaller than a standard drift value such as one-tenth of the optical absorbance measured for a spectrum of an analyzed sample at the detection wavelength. A standard noise value setting unit may be further provided for receiving detection signals at detection wavelength while a standard sample is placed inside a detection cell, calculating a standard noise value on the basis of intensity of the detection signals, and transmitting the calculated standard noise value to the stabilization judging unit.

Abstract: An adjustment circuit and method for reading a measurement output of an automotive oxygen sensor provide correction for outgassing of the sensor and inversion of the measurement output. The adjustment circuit includes a biasing stage connected to a sensor return of the oxygen sensor, where the biasing stage applies a predetermined bias voltage to the sensor return. An input stage is connected to an output of the sensor for retrieving the measurement output from the sensor. The adjustment circuit further includes an A/D conversion system connected to the input stage for adjusting the measurement output based on the bias voltage. The A/D conversion system may further be connected to the biasing stage for retrieving a sensor return output from the sensor. In such cases, a differential module calculates a difference between the sensor return output and the measurement output. The sensor return output defines an actual bias voltage applied to the sensor return.

Abstract: Method and apparatus for determining the concentration of an analyte gas using a gas measurement device comprising a gas sensing element having an electrical current output dependent upon concentration of a gas being measured, means for measuring the electrical output signal and means for limiting diffusion of the gas being measured to the gas measurement device and defining a path for gas being measured to enter the gas measurement device. Concentration is determined by exposing the gas sensing element to the analyte gas at a first rate of diffusion and diffusivity, and measuring the output signal for a time sufficient to establish a first steady state signal, reducing diffusion of gas to the gas sensing element to a second rate of diffusion and diffusivity, and measuring the output signal for a time sufficient to establish a second steady state signal, and calculating the concentration of the analyte gas based on the second diffusivity and the first and second steady state output signals.

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 gas concentration measuring apparatus is provided which measures the concentration of a given gas using a gas sensor. The gas sensor includes a sensor element producing a gas concentration signal indicative of the concentration of the gas, a heater heating the sensor element, and an insulator disposed between the sensor element and the heater. The apparatus includes a heater control circuit which may provisionally supply electrical power to the heater by applying a Pulse-Width-Modulated signal. The heater control circuit performs a switching operation to supply power to the heater cyclically. The apparatus corrects an error contained in the gas concentration signal arising from a leakage current flowing into the sensor element through the insulator during the switching operation of the heater control circuit.

Abstract: Method and apparatus for determining the concentration of an analyte gas using a gas measurement device comprising a gas sensing element having an electrical current output dependent upon concentration of a gas being measured, means for measuring the electrical output signal and means for limiting diffusion of the gas being measured to the gas measurement device and defining a path for gas being measured to enter the gas measurement device. Concentration is determined by exposing the gas sensing element to the analyte gas at a first rate of diffusion and diffusivity, and measuring the output signal for a time sufficient to establish a first steady state signal, reducing diffusion of gas to the gas sensing element to a second rate of diffusion and diffusivity, and measuring the output signal for a time sufficient to establish a second steady state signal, and calculating the concentration of the analyte gas based on the second diffusivity and the first and second steady state output signals.

Abstract: A gas concentration measuring apparatus is provided which measures the concentration of two kinds of gas components such as O2 and NOx contained in exhaust gasses of an internal combustion engine of automotive vehicles. The apparatus has a gas sensor which includes a first cell responsive to application of a voltage to discharge O2 in the exhaust gasses to the outside and produce an electric current as a function of concentration of the discharged O2 and a second cell responsive to application of a voltage to produce an electric current as a function of concentration of NOx in the exhaust gasses from which the O2 is discharged by the first cell. The apparatus offsets an error component of the electric current produced by the second cell which depends upon O2 contained in the exhaust gasses, or which in related operations, depends upon any residual oxygen remaining in the second cell without being discharged by the first cell.

Abstract: A method of operating a gas sensor having two sensor electrodes whose output signal is evaluated in an evaluation circuit connected downstream of the sensor electrodes, the sensor electrodes being arranged in an ion-conducting ceramic and being therefor heated by an electrical heater, characterized in that a pulsewidth modulated heater voltage signal is applied to the heater; and that a compensation signal is superposed on the output signal of the sensor electrodes, the compensation signal being essentially formed so as to be counterclocked and inverted to the pulsewidth modulated heater voltage signal.

Abstract: The invention relates to a method for compensating measured concentration values of a first chemical compound (A) within a first internal tract (1*) of a patient, which concentration values (PA) are rendered by a second chemical compound (B), which is becoming present in the body of said patient, to deviate from actual concentration when mixing with the first chemical compound within said first internal tract. Concentration values (EB) of at least said second chemical compound (B) in a second tract (2*) of said patient is measured or derived several times and estimated concentration values (CB) of said second chemical compound is determined simulating its non-detected concentrations in said first internal tract of the patient. The measured initial concentration values (PA) of said first chemical compound (A) in the first internal tract (1*) is corrected by a compensating factor (Fc), whereafter said successive and corrected concentration values (CA) are the respective one for display and/or further use.

Abstract: In order to correct the characteristic of a linear lambda probe which is arranged in an emission control system of an internal combustion engine upstream of a catalytic converter, in an overrun fuel cut-off phase the throttle valve and/or at least one gas exchange valve of the internal combustion engine is opened, and the signal of the lambda probe is assigned to the lambda value corresponding to the oxygen concentration of the ambient air. It is then possible, together with a conventional trimming controller which corrects the assignment of the signal to lambda=1, to correct the gradient of the characteristic.

Abstract: An improved apparatus and method for measuring the concentration of hydrogen peroxide vapor or gas in a sterilization chamber. The hydrogen peroxide is measured spectrophotometrically in the ultraviolet region between 200 and 400 nm. Because water vapor does not absorb in the ultraviolet region, it does not interfere with the determination of the concentration of the hydrogen peroxide vapor. Although organic compounds have absorbances in the ultraviolet region, the organic compounds are removed by evacuating the sterilization chamber to low levels before doing the hydrogen peroxide determination. The ultraviolet light source is either a low pressure mercury vapor lamp with an emission at 254 nm or a deuterium lamp with an optical filter selective of 206 nm light. A movable gas cell can be used to measure the hydrogen peroxide concentration at various areas in the sterilization chamber.

Abstract: The fuel gas or a substream of the fuel gas is passed through a volumetric flowmeter and the volumetric gas flow is measured. In addition, the pressure, temperature and the proportion of at least one inert gas as well as the density and the dielectric constant are measured under reference conditions. The amount of heat supplied to gas consumption devices can be determined from these six parameters reliably without complicated technology.

Abstract: A method and apparatus for measuring differential and absolute concentrations of a selected gas, preferably oxygen, in two flowing gas streams is described. A reference gas and a sample gas in separate gas flow paths are passed at selected temperature, pressure and flow rate over a pair of gas sensors, connected in series with their cathodes or anodes connected together, which produce output signals proportional to the differential selected gas concentration between the sensors and the absolute selected gas pressure in each sensor. The output signals may be amplified and recorded by any conventional means.

Abstract: A multi-element fluid sensor system having a distributed sensor configuration for determining the health state of a fluid. The sensor system includes at least two sensors for collecting data relating to a particular parameter (e.g., pH, temperature, electrical conductivity, chemistry, viscosity) of the fluid. The at least two sensors may be integrated onto a semiconductor base so as to provide for a micro sensor for in situ monitoring of the fluid. The system also includes a data fusion processor operatively coupled to the at least two sensors. The data fusion processor processes the fluid data to at least compensate for information fragmentation attributed to using the at least two sensors. The data fusion processor may condense the data, combine the data, evaluate the data and interpret the data.

Abstract: A reliable gaseous hydrogen detection and measuring device which is simple, easy to use, does not require any reference gas supply, and which can be of reasonably rugged construction. The device utilizes a disc comprising a solid state ceramic hydronium conductor of the general formula Na(H3O)Zr2SixP(3−x)O12 Na(H3O)xZr2SixP(3−x)O12 together with a silver based electrode system on one side, and a catalytic noble metal electrode, such as platinum, on the other. By measurement of the output voltage across the electrodes, both the presence, and the amount, of hydrogen in a gaseous system can be determined.