Abstract: A carbon dioxide sensitive material including a polymer binder, a plasticiser, a lipophilic organic quaternary cation, an indicator dye anion and an aromatic alcohol in such concentration that the material changes color in accordance with the concentration of carbon dioxide.

Abstract: An apparatus and method for visually and continuously monitoring gaseous concentrations of electrophiles such as carbon dioxide. A coating composition comprising an organic binder, filler/pigment, an activator, and carbon dioxide sensitive color indicator interacts with a primed substrate to which it is applied for support. The coated primed substrate may then be used for estimation of carbon dioxide concentration by the detection of a substantially instantaneous and reversible color change of the coated primed substrate.

Abstract: The isotopic composition of a multiatomic isotope-bearing species such as CO.sub.2 in an analyte is measured by maintaining the analyte in a condition such that isotope-bearing species are present in an excited state and directing light at wavelengths corresponding to transition energies of isotope-bearing species with different isotopes. The interaction between the analyte and light at the different wavelengths is monitored, as by monitoring the optogalvanic effect caused by the light of the different wavelengths. The light may be supplied by a laser including the isotope-bearing species. A stable isotope such as .sup.13 C or .sup.18 O can be used as a tracer in a chemical or biological test and detected using the composition-determining method.

Abstract: A monitoring device system and a method for controlling ventilation in an enclosed or confined environment by regulating the effective ventilation rate, air exchange rate, mixing factors, stratification of air within the confined area, the percentage of outside air which is introduced (when possible), the percentage of recirculated air, mean air life, air half-life are described. The device may be used for controlling an HVAC system so that air quality conforms to predetermined air quality standards. The monitoring device consists of a multiport sample collection system and one or more sensors to detect determinants of air quality. The method of control uses a CPU to regulate fans, dampers, and other systems to maintain the air quality within predetermined ranges, based upon the monitoring data. A tracer gas, preferably CO.sub.2, is used to determine system parameters.

Abstract: A transition metal oxide based calorimetric non-methane hydrocarbon sensor (100) is constructed by disposing a transition metal based catalyst (105), preferably chromium oxide (Cr.sub.2 O.sub.3), onto a carrier (101). A temperature measurement device (103) is positioned thermally coupled to the transition metal based catalyst (105). A preferred application includes sensing non-methane heavy hydrocarbons in an automotive exhaust gas stream (803) by exposing a transition metal oxide catalyst based sensor (805) to the exhaust gas stream (803) and providing a signal (811) indicative of a concentration of non-methane heavy hydrocarbons and carbon monoxide (CO). Then, exposing a compensating sensor (807) to the same exhaust gas stream (803) and providing a compensating signal (813) indicative of a concentration of carbon monoxide (CO). By combining the signal (811) and the compensating signal (813), a measure of non-methane heavy hydrocarbons can be provided.

Abstract: To determine the total organic carbon content of a flowing liquid in a continuous process, water and oxidizing agents enter lower ports in a multi-stage column and flow upwardly through residence chambers as they are mixed. Spaced apart along the upper path of the liquid, there are helical reaction grooves relatively shallow and containing at least one helical groove to cause rapid motion of the liquid. An ultraviolet lamp extends downwardly through the center of the column so that the outer confining surface of the helical grooves is the outer surface of the ultraviolet lamp, causing the liquid to move rapidly in intimate contact with the ultraviolet lamp to receive intense radiation. The stages are separate and interchangeable so that selected sizes may interconnect. The residence chambers may have different sizes to permit different lengths of residence time and thus permit tailoring of the reaction to the expected organic carbon content and possible side reactions with other impurities in the water.

Abstract: A capnometer is disclosed with a light sourse for irradiating a respirtory gas, a thermal detector for sensing the transmission of the infrared radiation, a switch device for turning the radiation source on and off in a predetermined period, a memory device for storing output from the thermal deterctor, and a control device for picking up a maximum value of the detection signal from the thermal detector for the present inspiration phase. The maximum value is stored in the memory device and the difference is calculated between a subsequently issued detection signal and the stored maximum value to compensate for drift that has occurred in the thermal detector.

Abstract: An NOx sensor has the sensor element made of an oxide, the resistance of which is varied in response to an NOx component in a gas to be measured, and a measuring portion for measuring a resistance variation of the sensor element and for detecting an NOx concentration in the gas to be measured. A catalyst is arranged at an upstream side of a flow of the gas to be measured with respect reach to the sensor element, which makes a partial pressure ratio of NO/NO.sub.2 reach to an equilibrium state and removes a CO component from the gas to be measured. A heater for adjusting a temperature is arranged at a position close to the sensor element, which maintains temperatures of the sensor element and the catalyst constant. An O.sub.2 sensor is arranged at a position close to the sensor element so that the measuring portion can detect accurately the concentration of Nox in the measurement gas by reference to the resistance of the sensor element.

Abstract: A method for making measurements of the O.sub.2 and CO.sub.2 dissolved in a urine sample to determine the identity and the age of the specimen.

Abstract: An improved measurement cell and circuit for measuring the electrical characteristics of a liquid sample during exposure to radiation includes a glass cell formed of a main tube extending generally parallel to an elongated lamp emitting the radiation, and a pair of electrodes disposed axially within the sample tube. In the preferred embodiment, the ends of the cell are formed of glass twinbore tubing fused to the glass main tube, the bores retaining ends of the electrodes. Inlet and outlet tubes and a temperature sensing well may also be fused to the main tube. In an implementation for measurement of TOC in water by oxidation to CO.sub.2, the source comprises a low pressure mercury vapor lamp, and the electrodes are formed of solid Ti with catalytic TiO.sub.2 surfaces.

Abstract: A simultaneous dual excitation/single emission ratiometric method using fiber optic sensors is provided for detecting or measuring a parameter of interest in a sample, including pH, concentration of gases such as CO.sub.2, and the like. The method involves simultaneously providing modulated optical light corresponding to first and second regions of an indicator species' absorption or excitation spectrum, detecting modulated emission signals from the indicator species, demodulating the emission signals, calculating the apparent quantity of analyte present in the sample from the indicator emission signals and correcting the apparent quantity of analyte present for variations resulting from external factors, by determining the ratio of the demodulated indicator emission signals. An apparatus is provided for performing the method as well.

Abstract: A halogenated hydrocarbon (HHC) detector is formed from a silent discharge (also called a dielectric barrier discharge) plasma generator. A silent discharge plasma device receives a gas sample that may contain one or more HHCs and produces free radicals and excited electrons for oxidizing the HHCs in the gas sample to produce water, carbon dioxide, and an acid including halogens in the HHCs. A detector is used to sensitively detect the presence of the acid. A conductivity cell detector combines the oxidation products with a solvent where dissociation of the acid increases the conductivity of the solvent. The conductivity cell output signal is then functionally related to the presence of HHCs in the gas sample. Other detectors include electrochemical cells, infrared spectrometers, and negative ion mobility spectrometers.

Abstract: A method for determining pH or pCO.sub.2 using luminescent lifetimes and energy transfer in which an energy transfer donor-acceptor pair is exposed to a sample to be analyzed, the donor of the donor-acceptor pair being photoluminescent and the acceptor of the donor-acceptor pair being sensitive to the pH or pCO.sub.2 of the sample. One or both of the donor-acceptor pair may be bound to a carrier. The sample is irradiated and the resultant emission detected. By measuring the apparent luminescent lifetime, the pH or pCO.sub.2 of the sample can be determined.

Abstract: The process of this invention comprises providing a membrane for separating CO.sub.2 into a first CO.sub.2 sample phase and a second CO.sub.2 analyte phase. CO.sub.2 is then transported through the membrane thereby separating the CO.sub.2 with the membrane into a first CO.sub.2 sample phase and a second CO.sub.2 analyte liquid phase including an ionized, conductive, dissociated CO.sub.2 species. Next, the concentration of the ionized, conductive, dissociated CO.sub.2 species in the second CO.sub.2 analyte liquid phase is chemically amplified using a water-soluble chemical reagent which reversibly reacts with undissociated CO.sub.2 to produce conductivity changes therein corresponding to fluctuations in the partial pressure of CO.sub.2 in the first CO.sub.2 sample phase. Finally, the chemically amplified, ionized, conductive, dissociated CO.sub.2 species is introduced to a conductivity measuring instrument. Conductivity changes in the chemically amplified, ionized, conductive, dissociated CO.sub.

Abstract: The present invention provides an optical fluorescence based sensor for measuring the concentration of a gas (e.g., CO.sub.2 or ammonia) in a medium such as blood which has improved drift stability. In a preferred embodiment, the sensors of the present invention comprise microcompartments of an aqueous phase having a pH sensitive sensing component within a hydrophobic barrier phase. The sensors of the present invention are substantially free of partitioning species other than the analyte of interest which can migrate from one phase to the other in response to a change in pH in the aqueous phase and which substantially affect the concentration dependent signal. In an alternative embodiment, the sensors of the present invention are constructed so as to retard the migration of partitioning species, thus reducing the initial rate of drift.

Abstract: Non-toxic combustion decomposition accelerators and processes for their production for elemental analysis. The non-toxic accelerators may be either single component or multicomponent. The single component non-toxic accelerators are glass frit, niobium pentoxide, and inorganic phosphate compounds. The multicomponent accelerators are formed from a combination of the foregoing, and most preferably from (a) one or more of niobium pentoxide, tungsten oxide and mixtures thereof, and (b) one or more of glass frit, inorganic phosphate compounds, and mixtures thereof.

Abstract: The invention pertains to a method for generating the fluorescence of polyanionic fluorophores in low dielectric media with fluorescence activation produced by specific quaternary onium compounds. The method may be used for measuring an analyte and may be useful in sensor devices.

Abstract: The detector which provides a detectable indication of the presence of an elevated proportion of carbon dioxide compared to that in normal ambient air, comprises a substrate coated by an intimate mixture of a transparent plasticised polymer vehicle, and an indicator material which undergoes a color change on exposure to carbon dioxide. The indicator material comprises an anionic fluorimetric dye and a lipophilic organic quaternary cation.

Abstract: The monitor which provides a detectable indication of the presence of an elevated proportion of carbon dioxide compared to that in normal ambient air, comprises a substrate coated by an intimate mixture of a transparent plasticised polymer vehicle, and an indicator material which undergoes a colour change on exposure to carbon dioxide. The indicator material comprises a salt of an indicator anion and a lipophilic organic quaternary cation. The device can be used to provide an indication of correct intubation of the trachea of a patient.

Abstract: A gas indicator (11) for a modified atmosphere food package (19) comprises a series of strips (12, 13, 14, 15, 16) which progressively change colour as the proportion of carbon dioxide in the atmosphere progressively changes in magnitude due to absorption of the carbon dioxide by the food product (17) over time. The indicator (11) thus is "tuned" to indicate changing atmospheric conditions inside a see-through envelope (10) and thus the condition of the product (17) can be monitored and the package (19) is tamper evident.

Abstract: A carbon dioxide gas is supplied to a living plant while it is illuminated with excitation light, and resulting fluorescence from the plant is detected. Then, a mixture of a carbon dioxide gas and a gas or fine particles to be monitored is supplied to the same living plant while it is illuminated with the excitation light, and resulting fluorescence from the plant is detected. Differences between temporal variations or wavelength characteristics of fluorescence intensities under the above two conditions are used to identify the gas or fine particles.

Abstract: A carbon dioxide gas measurement and control system which comprises a thermal conductivity CO.sub.2 sensor and a humidity sensor which produce separate and independent output signals which are compared in a microprocessor, thereby generating a humidity compensated carbon dioxide gas measurement which is accurate to within .+-.0.1%.

Abstract: The present invention provides an optical fluorescence based sensor for measuring the concentration of a gas (e.g., CO.sub.2 or ammonia) in a medium such as blood which has improved drift stability. In a preferred embodiment, the sensors of the present invention comprise microcompartments of an aqueous phase having a pH sensitive sensing component within a hydrophobic barrier phase. The sensors of the present invention are substantially free of partitioning species other than the analyte of interest which can migrate from one phase to the other in response to a change in pH in the aqueous phase and which substantially affect the concentration dependent signal. In an alternative embodiment, the sensors of the present invention are constructed so as to retard the migration of partitioning species, thus reducing the initial rate of drift.

Abstract: A method and infrared sensing device for determining the concentration of alveolar alcohol in a breath sample exhaled by a subject into an infrared sensing device. The presence of alcohol from the upper respiratory tract of the subject is detected by continuously monitoring alcohol and carbon dioxide, normalizing alcohol values with respect to carbon dioxide, calculating a difference between normalized alcohol concentration and carbon dioxide concentration over time, integrating (summing) the difference, and comparing the integrated difference with a threshold. This technique accurately and consistently detects the presence of mouth alcohol in the sample before the presence of carbon dioxide which originates in deep lung breath.

Abstract: An apparatus for the analysis of carbon products enables air reactivity, CO.sub.2 reactivity, soot index and coefficient of thermal expansion of the carbon products to be determined in one analysis operation. The apparatus includes vertical and/or horizontal tube furnaces, each of which is provided with devices for weighing, temperature registration and/or registration dilation. Introduction of gas takes place via one end of each of the tube furnaces. Each of the furnaces is connected to a joint processing unit which checks the various instruments and registers the various instruments and registers and processes the analytical data.

Abstract: Sensing composition precursors and sensing compositions, useful in sensing the concentration of a gas, e.g., carbon dioxide, in a medium, e.g., blood, are disclosed. In one embodiment, the sensing composition precursor comprises a dispersed aqueous liquid including a sensing component dissolved therein, a polymer precursor, and a hydrophilic dispersing agent selected from hydroxyalkyl celluloses and mixtures thereof in an amount effective to facilitate maintaining the dispersed aqueous liquid.

Abstract: Carbon particulate concentration of diesel exhaust or other sampled gas is measured by collecting the particulate on a high efficiency filter while measuring the amount of sampled gas passing through the filter. The filtered particulate is then heated in an oxygen rich environment to oxidize carbon within the particulate to carbon dioxide. The amount of resulting carbon dioxide is measured with a closed measurement loop to derive a corresponding measurement of the amount of filtered particulate. Particulate concentration is calculated by comparing the amount of carbon particulate with the measured amount of sampled gas passed through the filter. Filtered particulate can be heated incrementally to obtain a measurement of volatile carbon components within the particulate prior to the oxidation of the non-volatile carbon component.

Abstract: Apparatus and methods for measurement of total organic carbon content of water, particularly of low relative organic content, are described, featuring a single sample cell for exposure of a static sample to ultraviolet radiation and comprising electrodes for measuring the conductivity of the water. The conductivity is monitored as a function of time and the second time derivative of the conductivity signal is monitored to indicate when the oxidation reaction has been completed. Compensation for the contribution to conductivity of the water sample made by the instrument is achieved by subtracting a quantity proportional to the first time derivative of the conductivity at a time when the second time derivative reaches zero, indicating that the oxidation reaction is complete, from the change in the total conductivity measurement, the remainder being equal to the contribution to conductivity made by oxidation of the organic content of the water.

Abstract: Europium activated magnesium oxide phosphors are described as useful photoluminescent materials, to be used in methods for detecting the presence or determining the concentration of carbon dioxide in a sample, comprising the steps of a) exposing to a predetermined wavelength range radiation a carbon dioxide-quenchable photoluminescent phosphor put in contact with the sample to cause the phosphor to store energy radiation, b) stimulating the photoluminescent phosphor with infrared radiation to release the stored energy as photoluminescent light, c) detecting and measuring the intensity of said photoluminescent light and d) correlating the measured intensity with an intensity of the photoluminescent light previously measured at a given reference carbon dioxide pressure value.

Abstract: A method and apparatus are described for an accurate determination of the concentration of a gas, vapor or a gas dissolved in a sample which compensate for variations in temperature and light - source intensity. The apparatus comprises a sensor containing a fluorescent reagent connected to a transfer optic, such as fiber optics prism or glas pipes, and to a reference sensor containing the same fluorescent reagent. The reference sensor is encapsulated in an environment containing air. The light emitted from the first sensor and the reference sensor is determined and recorded automatically, the concentration of the gas being calculated based on the output from said light detectors using calibration data of the fluorescent reagent present in the sensors. The reagent is immobilized in the sensor by a glue, such as a silicon glue.

Abstract: An apparatus and method for the measurement of low levels of carbon dioxide in a sample employing membrane separation and ion-exchange technology. The difference in acid strength of carbonic acid and other acids is exploited by treating the sample with a weak base in a membrane separator (10). In this manner, the carbonic acid is distinguished from the stronger acids.

Abstract: Apparatus and method for qualitatively and quantitatively analyzing infrared emission from excited molecules in samples of interest is disclosed. Over the wavelength interval from 1 to 5 um, two strong emission bands are observed with a PbSe detector when organic compounds are introduced into an hydrogen/air flame. The band at 4.3 um (2326 cm.sup.-1 is due to the asymmetric stretch of carbon dioxide while the band at 2.7 um is due to both water and carbon dioxide emission. The carbon dioxide emission at 4.3 um is most intense at the tip of the flame, and increases with the amount of organic compound introduced into the flame. For chromatographic application, an optical filter can be used to isolate the 4.3 um emission band. The infrared emission detection system finds application in the determination of total inorganic carbon, chloride and available chlorine in aqueous samples.

Abstract: The method of stabilizing a carbon dioxide sensor involves formulation of a bicarbonate buffer solution in the sensor with a bicarbonate ion concentration of from about 100 mM to about 200 mM bicarbonate. The method also involves treatment of the sensor to reduce the instability that may occur in carbon dioxide sensors when such sensors are exposed to either very low or very high carbon dioxide levels for extended periods of time. The sensor is treated by exposing the sensor to an aqueous solution containing at least 2 weight percent carbon dioxide, for from several days to several months. The solution may be prepared in advance, or may be dynamically infused with carbon dioxide to provide the desired carbon dioxide content.

Abstract: The solution for storage and calibration of an intravascular blood sensor is an aqueous solution of from 10-35 mM of a first buffer component of bicarbonate, and at least one additional buffer component selected to maintain the pH of the solution substantially at or slightly below a neutral pH, and preferably below approximately pH 8. The first and additional buffering components preferably are selected to act in two separate pH regions with substantially no overlap of the buffering capacity of the different buffering components, and the concentration of the first buffer component in the solution is selected to permit a two point calibration of the intravascular multiparameter blood sensor by carbon dioxide and oxygen gas tonometry.

Abstract: A method and apparatus are is disclosed for determining whether respiratory gas is present in a gaseous sample. The sample is brought into contact with an indicator which yields an indication within a diagnostically effective period of time of the presence in the sample of carbon dioxide in concentration of at least 2% while an indication of the presence of carbon dioxide or other trace acidic gas in a sample of ambient air is delayed beyond a predetermined period of time. The method and apparatus of the present invention have particular utility in determining the correct placement of an endotracheal catheter in a patient or in the direction of apnea.

Abstract: An apparatus and method for the measurement of low levels of carbon dioxide in a sample employing membrane separation and ion-exchange technology. The difference in acid strength of carbonic acid and other acids is exploited by first treating the sample with a weak base in a membrane separator and then with a strong base in the membrane separator. In this manner, the carbonic acid is distinguished from the stronger acids. By converting carbonic acid to sodium carbonate, the conductivity level is enhanced facilitating more precise measurements.

Abstract: A method is disclosed for determining whether respiratory gas is present in a gaseous sample by which the sample is brought into contact with an indicator which yields an indication within a diagnostically effective period of time of the presence in the sample of carbon dioxide in concentration of at least 2% while an indication of the presence of carbon dioxide in a sample of ambient air would be delayed beyond a predetermined period of time. The method has particular utility in determining the correct placement of an endotracheal catheter in a patient or in the detection of apnea.

Abstract: A method for determining the carbonate content of washing suspensions of flue gas desulfurization plants using limestone is carried out by first admixing the samples, being at a temperature of from 40.degree. C. to 70.degree. C., with an excess amount relative to the maximum possible sulfite content, of an iron(III) chloride solution for the oxidation of the sulfite to sulfate, and then by addition of an excess amount of sulfuric acid or another acid, measuring the amount of escaping gas corresponding to the carbonate content.

Abstract: A method for measuring the concentration of hydroxides in alkaline solutions in a remote location using the tendency of hydroxides to absorb carbon dioxide. The method includes the passing of carbon dioxide over the surface of an alkaline solution in a remote tank before and after measurements of the carbon dioxide solution. A comparison of the measurements yields the absorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to absorption fraction.

Abstract: An apparatus for detecting or measuring the concentration of an analyte gas in a gas sample, which apparatus comprises a donor polymer and a halogen-containing compound positioned to contact the analyte gas and capable of reacting with the analyte gas to yield halogen; and a method for using the apparatus.

Abstract: A carbon dioxide indicator for use in determining the proper placement of endotracheal tubes. The indicator is comprised of a pH-sensitive dye suspended in a predominantly hydrophilic polymer matrix. The indicator may be placed inside a tube or connector to form an indicator device. When the pH-sensitive dye changes color due to CO.sub.2 and moisture in exhaled air, the color change is visible from outside the device.

Abstract: Method for making a probe with a plurality (one or more) of optical fiber sensors containing colorimetric chemical indicators in gaps in the fibers, the fibers bent to provide good light transmission qualities. Apparatus for making a probe with a plurality of such optical fiber sensors. A probe with a plurality of such optical fiber sensors. A vacuum chuck for holding the ends of such fibers.

Abstract: Particulate concentration of diesel exhaust is measured by collecting the diesel particulate on a filter while measuring the amount of exhaust passing through the filter. The filtered particlate is then heated in an oxygen rich enviroment to oxidize carbon within the particulate to carbon dioxide. The amount of resulting carbon dioxide is measured to derive a corresponding measurement of the amount of filterd particulate. Particulate concentration is calculated by comparing the amount of particulate with the measured amount of exhaust passed through the filter. Filtered particulate can be heated incrementally to obtain a measurement of volatile components within the particulate prior to the oxidation of the non-volatile carbon component. The filter employed to collect the particulate is of a high temperature resistant type making it reusable and can be either integral with or inserted into the oxidation chamber of the instrument.

Abstract: For the simultaneous measurement of two parameters of a liquid or gaseous sample, in a fluorescence measuring device in which the influence of the aging processes of the indicator substance and the fluctuations in the light intensity of the excitation light source are to be avoided, it is proposed that the change in the first parameter to be measured is obtained from the change in the ratio of two intensity values, determined for different wavelengths of the excitation and emission spectrum of the indicator substance, and the change of a second parameter is obtained from the change in the decay time t of the fluorescence radiation of the same indicator substance from the group of aromatic hydrocarbons, the aromatic heterocycles and the metal organic complexes.

Abstract: A method for analyzing fluid by a multi-fluid modulation mode is characterized by subjecting a plurality of sample fluids (which may be different or a single sample fluid divided into a plurality of systems) to a fluid modulation by reference fluids at various frequencies, respectively. An analytical portion provided with only one sensor is simultaneously and continuously supplied with the respective sample fluids. An output signal from the sensor in the analytical portion is divided into signal components of the respective modulation frequencies for the respective sample fluids to rectify and level, whereby obtaining analyzed values about the respective sample fluids is achieved.

Abstract: A method for determining the function of a unique cytochrome activity of the type which uniquely catalyses the N-demethylation of erythromycin in a patient's body, the method including the steps of ingesting a known quantity of a N-methyl carbon labeled erythromycin solution, the N-methyl carbon demethylated from the erythromycin being metabolized to an exhaled carbon labeled metabolite. A sample of exhaled breath containing a known amount of exhaled carbon metabolite is collected at a known interval of time after ingestion of the erythomycin solution. The quantity of labeled carbon metabolite is detected in the exhaled sample to determine the rate of labeled carbon elimination after the known time interval as an indication of the unique cytochrome function.

Abstract: A sensor system for determining the pH or carbon dioxide concentration of a liquid medium comprising, in combination, a pH-insensitive fluorescent indicator and a PH-sensitive fluorescent indicator which act in concert or a single fluorescence indicator which emits fluorescent signals of different wavelengths in different carriers, which system(s) produce diverging signals, the ratio of which provides an accurate and stable determination of the parameter being measured. A method for determining pH and CO.sub.2 concentration is also disclosed.

Abstract: An apparatus and method for the measurement of low levels of carbon dioxide in a sample employing membrane separation and ion-exchange technology. The difference in acid strength of carbonic acid and other acids is exploited by first treating the sample with a weak base in a membrane separator and then with a strong base in the membrane separator. In this manner, the carbonic acid is distinguished from the stronger acids. By converting carbonic acid to sodium carbonate, the conductivity level is enhanced facilitating more precise measurements.

Abstract: A gas detector system for detecting gases such as CO.sub.2. Sample air is passed through a critically sized sealed sample chamber in a sample cell. Infrared waves are generated in an insulated heater assembly, and radiate through windows of the sealed sample chamber concurrent with the sample air. The strength and magnitude of the infrared waves is attenuated by the level of gas, such as CO.sub.2, present in the sample air passing through the critically sized sealed sample chamber, and is sensed by a thermopile detector, including a filter for a specific frequency of infrared energy. Electronic circuitry processes the thermopile signal and measures other parameters of the gas detector to provide a signal indicative of the percentage of gas concentration in the air. Extensive use of insulation about and around the thermopile detector electronic circuitry and other components of the detector maximize stability and reliability.

Abstract: Colorimetric, fiber optic sensors for measuring pH, PCO.sub.2 and/or other chemical parameters of the blood. The sensors are fabricated using a single optical fiber, which is provided with a chamber at its distal end containing a pH sensitive dye. Located distal to the chamber is a white reflective surface located within 0.04" from the end of the optical fiber, which enhances the performance of the sensor.