Polarographic oxygen sensors
Polarographic oxygen sensors, which were originally developed for measuring oxygen in space cabin atmospheres, are examined for their use in medical, scientific, and industrial applications.
Source record↗
SEARCH · Search NASA
Results for “OXYGEN SENSOR”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Development and Performance of the Oxygen Sensor in the CSA-CP Aboard the International Space Station
A combustion products analyzer (CPA) was built for use on Shuttle in response to several thermodegradation incidents that had occurred during early flights. The CPA contained sensors that measured carbon monoxide, hydrogen chloride, hydrogen cyanide, and hydrogen fluoride. These marker compounds, monitored by the CPA, were selected based upon the likely products to be released in a spacecraft fire. When the Toxicology Laboratory group at Johnson Space Center (JSC) began to assess the air quality monitoring needs for the International Space Station (ISS), the CPA was the starting point for design of an instrument to monitor the atmosphere following a thermodegradation event. The final product was significantly different from the CPA and was named the compound specific analyzer-combustion products (CSA-CP). The major change from the CPA that will be the focus of this paper was the replacement of an unreliable hydrogen fluoride (HF) sensor with an oxygen sensor. A reliable HF sensor was not commercially available, but as the toxicology group reviewed the overall monitoring strategy for ISS, it appeared that a portable oxygen sensor to backup the major constituent analyzer was needed. Therefore, an oxygen sensor replaced the HF sensor in the new instrument. This paper will describe the development, deployment, and performance of the CSA-CP oxygen sensor on both Shuttle and ISS. Also, data for CSA-CP oxygen sensor accuracy at nominal and reduced pressures will be presented.
Limero, Thomas↗
An Optical Oxygen Sensor for Long-Term Continuous Monitoring of Dissolved Oxygen in Perfused Bioreactors
For long-term growth of man1ITlalian cells in perfused bioreactors, it is essential to monitor the concentration of dissolved oxygen (DO) present in the culture medium to quantitate and control level of DO. Continuous measurement of the amount of DO in the cell culture medium in-line under sterile conditions in NASA's perfused bioreactor requires that the oxygen sensor provide increased sensitivity and be sterilizable and nontoxic. Additionally, long-term cell culture experiments require that the calibration be maintained several weeks or months. Although there are a number of sensors for dissolved oxygen on the market and under development elsewhere, very few meet these stringent conditions. An optical oxygen sensor (BOXY) based on dynamic fluorescent quenching and a pulsed blue LED light source was developed in our laboratory to address these requirements. Tris( 4,7 -diphenyl-l, 1 O-phenanthroline )ruthenium(II) chloride is employed as the fluorescent dye indicator. The sensing element consists of a glass capillary (OD 4.0 mm; ID 2.0 mm) coated internally with a thin layer of the fluorescent dye in silicone matrix and overlayed with a black shielding layer. Irradiation of the sensing element with blue light (blue LED with emission maximum at 475 nm) generates a red fluorescence centered at 626 nm. The fluorescence intensity is correlated to the concentration of DO present in the culture medium, following the modified non-linear Stern-Volmer equation. By using a pulsed irradiating light source, the problem of dye-bleaching, which is often encountered in long-term continuous measurements of tIns type, 'is minimized. To date we achieved sensor resolution of 0.3 mmHg at 50 mmHg p02, and 0.6 mmHg at 100 mmHg p02, with a response time of about one minute. Calibration was accomplished in sterile phosphate-buffered saline with a blood-gas analyzer (BGA) measurement as reference. Stand-alone software was also developed to control the sensor and bioreactor as well as to acquire data. Two HOXY sensors with a single calibration were employed to continuously monitor the DO in GTSF-2 medium during a Baby Hamster Kidney (BHK-21) cell culture in a Rotating Wall Perfused Vessel (RWPV) bioreactor for 90 days. HOXY sensors were located at the inlet to and outlet from the bioreactor. One of the sensors was placed between an oxygenator and the inlet to the bioreactor. The dissolved oxygen concentrations determined by both sensors were compared with those measured regularly with the BGA reference. The cell culture was maintained for 110 days. Sensor output was found to correlate well with the BGA data throughout the experiment, where the DO of the medium ranged between 25 and 50 mmHg at the bioreactor outlet and 90-130 mmHg at the bioreactor inlet. Measuring DO with the HOXY sensors versus the BGA reference indicated bias values of -2 mmHg and -15 mmHg, and precision values of +/-3mmHg and +/-16 mmHg at the bioreactor inlet and outlet, respectively.
Gao, F. G.↗
Integrated-Optic Oxygen Sensors
Compact optical oxygen sensors with self-calibration capabilities are undergoing development. A sensor of this type features a single-chip, integrated-optic design implemented by photolithographic fabrication of optical waveguides in a photosensitive porous glass. The porosity serves as both a matrix for retention of an oxygen-sensitive fluorescent indicator chemical and a medium for diffusion of oxygen to the chemical from the ambient air to be monitored. Each sensor includes at least one such waveguide exposed to the atmosphere and at least one covered with metal for isolation from the atmosphere. The covered one serves as a reference channel. In operation, the concentration of oxygen is deduced from the intensity and lifetime of the fluorescence in the exposed channel, with the help of calibration data acquired via the reference channel. Because the sensory chemical is placed directly in and throughout the cross section of the light path, approximately 99 percent of the light in the waveguide is available for interaction with the chemical, in contradistinction to only about 1 percent of the light in an optical sensor that utilizes evanescentwave coupling. Hence, a sensor of this type is significantly more sensitive.
Mendoza, Edgar A.↗
New electrolyte may increase life of polarographic oxygen sensors
Electrolyte increases life on oxygen sensors in a polarograph used for measuring the partial pressure of oxygen in a gas mixture. It consists of a solution of lithium chloride, dimethyl acetamide and water.
Albright, C. F.↗
Evaluation of the Linear Aerospike SR-71 Experiment (LASRE) Oxygen Sensor
The Linear Aerospike SR-71 Experiment (LASRE) was a propulsion flight experiment for advanced space vehicles such as the X-33 and reusable launch vehicle. A linear aerospike rocket engine was integrated into a semi-span of an X-33-like lifting body shape (model), and carried on top of an SR-71 aircraft at NASA Dryden Flight Research Center. Because no flight data existed for aerospike nozzles, the primary objective of the LASRE flight experiment was to evaluate flight effects on the engine performance over a range of altitudes and Mach numbers. Because it contained a large quantity of energy in the form of fuel, oxidizer, hypergolics, and gases at very high pressures, the LASRE propulsion system posed a major hazard for fire or explosion. Therefore, a propulsion-hazard mitigation system was created for LASRE that included a nitrogen purge system. Oxygen sensors were a critical part of the nitrogen purge system because they measured purge operation and effectiveness. Because the available oxygen sensors were not designed for flight testing, a laboratory study investigated oxygen-sensor characteristics and accuracy over a range of altitudes and oxygen concentrations. Laboratory test data made it possible to properly calibrate the sensors for flight. Such data also provided a more accurate error prediction than the manufacturer's specification. This predictive accuracy increased confidence in the sensor output during critical phases of the flight. This paper presents the findings of this laboratory test.
Ennix, Kimberly A.↗
Evaluation of the Linear Aerospike SR-71 Experiment (LASRE) Oxygen Sensor
The Linear Aerospike SR-71 Experiment (LASRE) was a propulsion flight experiment for advanced space vehicles such as the X-33 and reusable launch vehicle. A linear aerospike rocket engine was integrated into a semi-span of an X-33-like lifting body shape (model), and carried on top of an SR-71 aircraft at NASA Dryden Flight Research Center. Because no flight data existed for aerospike nozzles, the primary objective of the LASRE flight experiment was to evaluate flight effects on the engine performance over a range of altitudes and Mach numbers. Because it contained a large quantity of energy in the form of fuel, oxidizer, hypergolics, and gases at very high pressures, the LASRE propulsion system posed a major hazard for fire or explosion. Therefore, a propulsion-hazard mitigation system was created for LASRE that included a nitrogen purge system. Oxygen sensors were a critical part of the nitrogen purge system because they measured purge operation and effectiveness. Because the available oxygen sensors were not designed for flight testing, a laboratory study investigated oxygen-sensor characteristics and accuracy over a range of altitudes and oxygen concentrations. Laboratory test data made it possible to properly calibrate the sensors for flight. Such data also provided a more accurate error prediction than the manufacturer's specification. This predictive accuracy increased confidence in the sensor output during critical phases of the flight. This paper presents the findings of this laboratory test.
Ennix, Kimberly A.↗
Determining Performance Acceptability of Electrochemical Oxygen Sensors
A method has been developed to screen commercial electrochemical oxygen sensors to reduce the failure rate. There are three aspects to the method: First, the sensitivity over time (several days) can be measured and the rate of change of the sensitivity can be used to predict sensor failure. Second, an improvement to this method would be to store the sensors in an oxygen-free (e.g., nitrogen) environment and intermittently measure the sensitivity over time (several days) to accomplish the same result while preserving the sensor lifetime by limiting consumption of the electrode. Third, the second time derivative of the sensor response over time can be used to determine the point in time at which the sensors are sufficiently stable for use.
Gonzales, Daniel↗
Oxygen sensor optimization for long duration space missions
A new type of oxygen sensor is being developed for potential use in future manned space missions. This sensor incorporates two independent measurement schemes using dual electrochemical cells formed in a common body of solid electrolyte-zirconia. A combination of potentiometric and coulometric measurements yields accurate and fast response to cabin atmosphere oxygen. Means for self-calibration, fault detection and diagnosis by computer operation are discussed.
Taylor, R. M.↗
Calibration Of Partial-Pressure-Of-Oxygen Sensors
Report and analysis of, and discussion of improvements in, procedure for calibrating partial-pressure-of-oxygen sensors to satisfy Spacelab calibration requirements released. Sensors exhibit fast drift, which results in short calibration period not suitable for Spacelab. By assessing complete process of determining total drift range available, calibration procedure modified to eliminate errors and still satisfy requirements without compromising integrity of system.
Yount, David W.↗
Oxygen Sensors Monitor Bioreactors and Ensure Health and Safety
In order to cultivate healthy bacteria in bioreactors, Kennedy Space Center awarded SBIR funding to Needham Heights, Massachusetts-based Polestar Technologies Inc. to develop sensors that could monitor oxygen levels. The result is a sensor now widely used by pharmaceutical companies and medical research universities. Other sensors have also been developed, and in 2013 alone the company increased its workforce by 50 percent.
Source record↗
Design of an oxygen sensor with automatic self-testing and calibration capability
Future long duration manned space missions require a reliable sensor to monitor cabin oxygen (O2) pressure. This paper presents a concept for a solid zirconia O2 sensor capable of automatic self-test and calibration without the need for consumable materials. The operation and the techniques used to verify proper performance and to calibrate the sensor are described. Coulometric measurements are used to calculate the cabin O2 pressure without comparison to any reference state; potentiometric measurements are simple and reliable. The use of independent measurements permits the verification of results obtained with either technique. The design includes fault diagnostics which takes corrective action if a fault occurs.
Cusick, Robert J.↗
Silica Aerogels Doped with Ru(II) Tris 1,l0-Phenanthro1ine)-Electron Acceptor Dyads: Improving the Dynamic Range, Sensitivity and Response Time of Sol-Gel Based Oxygen Sensors
Complexes 1 and 2 were characterized in fluid and frozen solution and as dopants of silica aerogels. The intramolecular quenching efficiency of pendant 4-benzoyl-N-methylpyridinium group (4BzPy) is solvent dependent: emission is quenched completely in acetonitrile but not in alcohols. On the other hand, N-benzyl-N'-methylviologen (BzMeV) quenches the emission in all solvents completely. The differences are traced electrochemically to a stronger solvation effect by the alcohol in the case of 1. In fiozen matrices or absorbed on the surfaces of silica aerogel, both 1 and 2 are photoluminescent. The lack of quenching has been traced to the environmental rigidity. When doped aerogels are cooled to 77K, the emission shifts to the blue and its intensity increases in analogy to what is observed with Ru(II) complexes in media undergoing fluid-to-rigid transition. The photoluminescence of 1 and 2 from the aerogel is quenched by oxygen diffusing through the pores. In the presence of oxygen, aerogels doped with 1 can modulate their emission over a wider dynamic range than aerogels doped with 2, and both are more sensitive than aerogels doped with Ru(II) tris(1,l0- phenanthroline). In contrast to frozen solutions, the luminescent moieties in the bulk of aerogels kept at 77K are still accessible, leading to more sensitive platforms for oxygen sensors than other ambient temperature configurations.
Kevebtusm Bucgikas↗
Surface acoustic wave oxygen sensor
A surface acoustic wave (SAW) device that responds to oxygen pressure was developed by coating a 158 MHz quartz surface acoustic wave (SAW) device with an oxygen binding agent. Two types of coatings were used. One type was prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer containing the axial ligand. A second type was prepared with an oxygen binding porphyrin solution containing excess axial ligand without a polymer matrix. In the polymer based coatings, the copolymer served to provide the axial ligand to the oxygen binding agent and as a coating matrix on the surface of the SAW device. The oxygen sensing SAW device has been shown to bind oxygen following a Langmuir isotherm and may be used to measure the equilibrium constant of the oxygen binding compound in the coating matrix.
Collman, James P.↗
Solid State oxygen Sensor Development
To anticipate future long-duration mission needs for life support sensors, we explored the feasibility of using thin-film metal-oxide semiconductors. The objective of this task was to develop gas sensors for life support applications which would be suitable for long-duration missions. Metal oxides, such as ZnO, SnO2, and TiO2 have been shown to react with oxygen molecules. Oxygen lowers the metal oxide's electrical resistance. Critical to the performance is the application of the oxide in a thin film on an inert substrate: the thinner the film, the more readily the oxygen penetration and hence the more rapid and sensitive the sensor. Metal oxides are not limited to oxygen detection, rather, oxides offer detection and quantification applications to the complete range of gases of interest, not only for life support systems, but for propellants as well.
Cheung, Jeffery T.↗
Van de Graaff Irradiation Studies of Oxygen Sensor and Hydrated Zirconia Sorbent
Commercial-scale production of Mo-99 demands a facility-wide assessment of radiation-induced degradation across process equipment, instrumentation, and purification media. Key factors— total ionizing dose, dose rate, radiolysis-driven chemistry, thermal loads, activation, and any neutron-related effects—should inform material selection, shielding, and component layout. Purification materials (sorbents, resins, filters, seals, housing) require particular attention to ensure that irradiation does not alter selectivity or capacity, generate fines, or introduce leachables that could compromise Mo-99 purity or downstream Tc-99m generator performance. Dose mapping, accelerated irradiation testing, and studies of extractables/leachables together provide the basis for setting maintenance, calibration, and replacement intervals and for qualifying materials that retain mechanical integrity, chemical compatibility, and radiopurity over their service life.
36 MATERIALS SCIENCE↗
Hydrogen and oxygen sensor development
A reliable and low cost gas sensor was investigated for instantaneously detecting H2 in N2, H2 in air, and O2 in N2. The major portion of the research was spent in developing a sensor which would instantaneously detect H2 to + or - 50 ppm even in the presence of trace amounts of other gases. The experimental procedures used to provide the performance characteristics for the various oscillators are discussed describing the equipment with help of schematics and photographs where applicable. The resulting performance is given in graphical form. In some cases both hydrogen and helium may be present and since both of them effect gas sensors similarly, a method was found to determine the concentration of each. The methods developed are grouped into the following four broad categories: pure metal response, variation in heat conductivity, reduction methods, and exotic processes. From the above it was decided for the present to use a copper oxide reduction process as this process was demonstrated to be capable of determining the concentrations of hydrogen and helium respectively in a gas mixture with air or nitrogen.
Farber, E. A.↗
Synthesis and Characterization of Ru(II) Tris(1,1O-phenanthroline)-Electron Acceptor Dyads Incorporating the 4-benzoyl-N-methylpyridinium Cation or N-Benzyl-N'-methyl-viologen. Improving the Dynamic Range, Sensitivity and Response Time of Sol-Gel Based Optical Oxygen Sensors
The title compounds (1 and 2, above) were synthesized by Sonogashira coupling reactions of appropriate Ru(1I) complexes with the electron a cceptors. Characterization was conducted in solution and in frozen ma trices. Finally, the title compounds were evaluated as dopants of sol-gel materials. It was found that the intramolecular quenching efficie ncy of 4-benzoyl-Nmethylpyridinium cation in solution depends on the solvent: photoluminescence is quenched completely in CH,CN, but not i n methanol or ethanol. On the other hand, intramolecular emission que nching by 4-benzyl-N-methyl viologen is complete in all solvents. The difference between the two quenchers is traced electrochemically to t he solvation of the 4-benzoyl-Nmethylpyridiniums by alcohol. In froze n matrices or adsorbed on the surfaces of silica aerogel, both Ru(I1) complex/electron acceptor dyads of this study are photoluminescent, and the absence of quenching has been traced to the environmental rigi dity. When doped aerogels are cooled at 77 K, the emission intensity increases by approximately 4x, and the spectra shift to the blue, analogous to what is observed with Ru(I1) complexes in solutions undergoi ng fluid-to-rigid transition. However, in contrast to frozen solution s, the luminescent moieties in the bulk of aerogels kept at low tempe ratures are still accessible to gas-phase quenchers diffusing through the mesopores, leading to more sensitive platforms for sensors than o ther room-temperature configurations. Thus the photoluminescence of o ur Ru(I1) complex dyads adsorbed on aerogel is quenchable by O2 both at room temperature and at 77 K. Furthermore, it was also found that O 2 modulates the photoluminescence of aerogels doped with 4-benzoyl -N -methylpyridinium-based dyads over a wider dynamic range compared wi th aerogels doped with either our vislogen-based dyads or with Ru(I1) tris(1,lO-phenanthroline) itself.
Leventis, Nicholas↗