Carbon dioxide sensing sensor

Clayton W A 1993 Improved capacitive moisture sensors Sensors 10 16-22 Ishihara T et al 1991 Application of mixed oxide capacitor to the selective carbon dioxide sensor. I. Measurement of carbon dioxide sensing characteristics J. Electrochem. Soc. 138 173-6... 

Ishihara,T., Kometani, K., Hashida, M. and Takita, Y. (1991), AppUcation of Mixed Oxide Capacitor to the Selective Carbon Dioxide Sensor. Part 1. Measnrement of Carbon Dioxide Sensing Characteristics , Journal of the Electrochemical Society, 138,1,173-6. 

Ishihara T, Kometani K, Mizuhara Y, Takita Y (1991a) Mixed oxide capacitor of CuO-BaSnOj as a sensor for CO detection over a wide range of concentration. Chem Lett 20(10) 1711-1714 Ishihara T, Kometani K, Hashida M, Takita Y (1991b) Application of mixed oxide capacitor to the selective carbon dioxide sensor. I. Measurement of carbon dioxide sensing characteristics. J Electrochem Soc 138 173-176 Ishihara T, Kometani K, Mizuhara Y, Takita Y (1992) Application of a mixed oxide capacitor to the selective carbon dioxide sensor. II. COj sensing characteristics of a CuO-based oxide capacitor. J Electrochem Soc 139 2881-2885... 

Herber, S., Bomer, J., Olthuis, W., Bergveld, P. and van den Berg, A. (2005) A miniaturized carbon dioxide gas sensor based on sensing of pH-sensitive hydrogel swelUng with a pressure sensor. Biomedical Microdevices, 7,197-204. 

The barium cerate electrolyte has also been investigated for application in a carbon dioxide gas sensor. The details of the sensing performance are described in sect. 6. 

The analytes typically determined by using this type of sensor are those usually addressed by gas-diffiision systems, viz. ammonia (or ammonium ion), carbon dioxide (or carbonates) and oxygen. The detection system used is most frequently photometric, fluorimetric or potentiometric, and can be integrated with or connected to the sensing microzone. The description below is based on the two choices shown in Fig. 5.4. 

The original design was developed specifically for sensing of carbon dioxide (Severinghaus, 1965), but the principle on which these gas sensors operate is general. The key element is a small compartment into which the gas can penetrate through a semipermeable membrane (Fig. 6.28). 

Pannell and coworkers34 described the use of poly(ferrocenylsilanes) as coatings in optical fiber gas sensors. In these devices a small change in refractive index of the polymer film results in a large change in the optical transmission of a tapered optical fiber. This is useful for remote sensing of ammonia or carbon dioxide. Polymers of type 6.20 with R/R = Me/Ph and copolymers from monomers with R/R = Me/Ph and Me/Me were found to be effective for this application. 

The first gas-sensing electrode based on a similar principle was the carbon dioxide electrode, developed to determine CO2 in blood. Later, sensors for other gases (e.g., SO2, NOx, and HCN, etc.) appeared on the market. 

Fonong and Rechnitz (1984a) entrapped the enzyme physically with a dialysis membrane at the sensing tip of a carbon dioxide selective electrode. The sensor was suitable for salicylate concentrations in the range 0.04-2.2 mmol/l. 

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... 

A characteristic of a control system where the signal must be sensed remotely and then the control action must occur remotely, perhaps at a third location, is that there are time delays built into the system. This is especially evident where the signal is a chemical produced someplace, and the chemical is transported to the sensor via a flow system (such as the blood). We have seen in Section 4.4 that Cheyne-Stokes breathing results from a long time delay somewhere in the loop. For the case where carbon dioxide is produced in the muscles and must be transported by the blood to chemoreceptors in the neck, there can be a 30 s or more delay between the onset of exercise and the signal to increase respiration. This may not be too bad in some circumstances, but, apparently, it led to disastrous consequences for our forebears. The respiratory system adjusts to the onset of... 

The SiC FET devices as high-temperature gas sensors are commercially available in sensor systems for combustion control in small- and medium-scale power plants. Recent research and development which started in 2009 has realized tailor-made sensing layers for oxygen and carbon dioxide detection. Smart sensor operation using only one sensor may detect the NOj... 

---