Cell, carbon dioxide sensor

GSSs are purposefully designed electrochemical cells, a galvanic cell in the case of carbon dioxide sensors, and an electrolytic cell in the case of the oxygen sensors. 

Constantine H P, Crow M R and Forster R E 1965 Rate of the reaction of carbon dioxide with human red blood cells Am. J. Physiol 208 801-11 Lutmann A, Miickenhoff K and Loeschcke H H 1978 Fast measurement of the CO2 partial pressure in gases and fluids Pfluegers Arch. Ges. Physiol 375 279-88 Wu X-Q, Shimizu Y and Egashira M 1989 Carbon dioxide sensor consisting of K2C03-polyethylene glycol solution supported on porous ceramics J. Electrochem. Soc. 136 2892-5... 

Abstract Applications of five-membered ring products in cyclometalation reactions for other purposes include organic electronic devices, pharmaceuticals, dye-sensitized solar cells, carbon dioxide utilizations, sensors, dendrimers, liquid crystals, resolving agents, and photosensitizers for hydrogen production. 

Mounting electrodes in a bioreactor is costly, and there is an additional contamination risk for sensitive cell cultures. Some other sensors of prac ticai importance are those for dissolved oxygen and for dissolved carbon dioxide. The analysis of gas exiting from a bioreactor with an infrared unit that detects carbon dioxide or a paramagnetic unit that detects oxygen (after carbon dioxide removal) has been replaced by mass spec trophotometry. Gas chromatographic procedures coupled with a mass spectrophotometer will detect 1 the volatile components. 

Carbon monoxide and carbon dioxide can be measured using the FTIR techniques (Fourier transform infrared techniques see the later section on the Fourier transform infrared analyzer). Electrochemical cells have also been used to measure CO, and miniaturized optical sensors are available for CO 2 monitoring. 

Yeast cells are able to metabolize many types of sugars. In this experiment, you will observe the fermentation of sugar by baker s yeast. When yeast cells are mixed with a sucrose solution, they must first hydrolyze the sucrose to glucose and fructose. Then the glucose is broken down in the absence of oxygen to form ethanol and carbon dioxide. You can test for the production of carbon dioxide by using a CBL pressure sensor to measure an increase in pressure. 

Reflectance measurements provided an excellent means for building an ammonium ion sensor involving immobilization of a colorimetric acid-base indicator in the flow-cell depicted schematically in Fig. 3.38.C. The cell was furnished with a microporous PTFE membrane supported on the inner surface of the light window. The detection limit achieved was found to depend on the constant of the immobilized acid-base indicator used it was lO M for /7-Xylenol Blue (pAT, = 2.0). The response time was related to the ammonium ion concentration and ranged from 1 to 60 min. The sensor remained stable for over 6 months and was used to determine the analyte in real samples consisting of purified waste water, which was taken from a tank where the water was collected for release into the mimicipal waste water treatment plant. Since no significant interference fi-om acid compounds such as carbon dioxide or acetic acid was encountered, the sensor proved to be applicable to real samples after pH adjustment. The ammonium concentrations provided by the sensor were consistent with those obtained by ion chromatography, a spectrophotometric assay and an ammonia-selective electrode [269]. 

Pattison RN, Swamy J, Mendenhall B, Hwang C, Frohlich BT (2000), Measurement and control of dissolved carbon dioxide in mammalian cell culture processes using an in situ fiber optic chemical sensor, Biotechnol. Prog. 16 69-74. 

In a few cases, small optical infrared absorption monitors have been integrated into electronic nose sensors [11], mostly for detection of the carbon dioxide evolution from cells. The 3000-4000 nm filters are normally used. 

Biosensors. Sensors are required to adequately monitor bioreactor performance. Ideally, one would like to have online sensors to minimize the number of samples to be taken from the bioreactor and to automate the bioreactor process. Most bioreactors have autoclavable pH and dissolved oxygen (D.O.) electrodes as online sensors, and use offline detectors to measure other critical parameters such as glucose and glutamine concentration, cell density, and carbon dioxide partial pressure (pC02). An online fiber-optic-based pC02 sensor is commercially available and appears to be robust.37 Probes are also commercially available that determine viable cell density by measuring the capacitance of a cell suspension. Data from perfusion and batch cultures indicate that these probes are reasonably accurate at cell concentrations greater than 0.5 X 106 cells/mL.38,39... 

The bath was turned on the day before the experiments. The equilibrium cell and all the lines were first evacuated. Then, the liquid heavy component was loaded from a scaled glass tank above valve V7. Carbon dioxide was finally pumped into the cell from a cooled storage unit through valves VI and V3 until the desired level of pressure was attained. The pressure was measured by a Data Instruments pressure tranducer model AB (range 5000 psi) with an accuracy of 0.1 bar. The temperature inside the cell was measured by a thermoresistance sensor (PT100Q) within + 0.1 °C. 

Extensive research and development of microbial sensors has been carried out by Suzuki et al. (89-94) and Rechnitz et al. (95-97) (see Table III). Microbial sensors consisting of membrane-bound whole cells and an oxygen electrode were constructed for the determination of substrates such as assimilable sugars, acetic acid, alcohols and ammonia, and for the estimation of biochemical oxygen demand (BOD) (98-104). Glutamic acid was determined with a microbial sensor which consists of membrane-bound whole cells containing glutamate decarboxylase and a carbon dioxide gas electrode. These microbial sensors have been applied and evaluated for on-line measurements in fermentation processes (105,106). 

Gas sensors (e.g., for sensing air quality, for measuring carbon dioxide in new types of air conditioning systems, for detecting ozone or fuel-cell gases such as... 

Besar S S A, Kelly S W and Greenhalgh P A 1989 Simple fibre optic spectrophotometric cell for pH determination J. Biomed. Eng. 11 151-6 Kawabata Y, Kamichika T, Imasaka T and Ishibashi N 1989 Fiber-optic sensor for carbon dioxide with a pH indicator dispersed in a poly(ethylene glycol) membrane Anal. Chim. Acta 219 223-9... 

A major focus of more recent studies on adsorption at metal electrodes has been the investigation of the mechanism of electro-oxidation of organic fuels (methanol, formic acid, formaldehyde, etc. [55, 56]) and the electro-reduction of carbon dioxide. The former type of reaction is important in the context of the development of fuel cells a major problem has been the poisoning of the anode by carbon fragments and mechanistic insights are urgently needed. In the latter case, the development of C02 sensors has a high priority. 

The need addressed by this project is for a sensor to detect the presence of CO in the H2 produced from hydrocarbon feedstocks in reformers and used to power PEM fuel cells. Low-cost sensors are not available for measuring CO at 1-100 ppm levels in a fuel cell environment. The primary goal of this project is to develop a low-cost microelectronic gas sensor for detecting CO (1-100 ppm) in the fuel stream. The sensors must operate in hydrogen (30-75%), with carbon dioxide (CO2) (15%), CO (0-... 

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