Chemical sensors carbon dioxide

Leiner, M. J. Tusa, J. Klimant, I. Dry optical-chemical carbon-dioxide sensor. U.S. Pat. Appl. Publ. US 20090004751, 2009. 

Chu, C. S. and Lo, Y. L. (2008) Fiber-optic carbon dioxide sensor based on fluori-nated xerogels doped with HPTS , Sensors and Actuators B-Chemical, 129(1), 120-125. 

Desai, R.R., Lakshminarayana, D., Ratel, R.B. and Ranchal, C.J. (2005), Indinm ses-quitelluride (In2Te3) thin film gas sensor for detection of carbon dioxide . Sensors and Actuators B Chemical, 107,2,523-7. 

There has been much effort in recent years to provide continuous chemical monitoring of critically ill patients or patients undergoing heart surgery. It has proved very difficult to fulfill the increased demands in such applications by any sensors. Some of the problems are sensor sterilization and calibration, effect of varying temperatures, sensor deterioration or cellular encapsulation due to continuous direct contact with blood, thrombogenicity of the sensor devices, small size, and patient safety. Noninvasive systems, e.g., transcutaneous oxygen and carbon dioxide sensors, are less affected and have had considerable success, particularly in infant care. O2 and CO2 can diffuse across the mildly heated skin to the sensors and the measured values correlate well with arterial samples. 

Industrial Applications Carbon-dioxide sensor - chemical sensors based on non-linear optics monitoring of cationic photopolymerization processes nanomaterials ... 

A few other optical chemical sensors for food applications are under development. Thus, sensors for carbon dioxide are in high demand, as the... 

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. 

There are various potential applications of photophysical phenomena in analytical chemistry. The relatively short lifetimes of most excited states, however, is a serious drawback to the construction of practical devices but studies which focus on finding ways to extend triplet lifetimes have now been described by Harriman et al. Kneas et al. have examined new types of luminescent sensor on polymer supports, and both Neurauter et al. and Marazuela et al. have designed sensors based on the ruthenium(II) polypyridine complex for the detection of carbon dioxide. A system, based on the formation of twisted intramolecular charge transfer states, has been devised for measuring the molecular weight of polymeric matrices (Al-Hassan et a/.), and the chemical reactivity at the interface of self-assembled monolayers has been assessed using fluorescence spectroscopy (Fox et al). 

Combined electrodes have been developed to measure dissolved gases such as carbon dioxide (CO2), ammonia (NH3) and sulfur dioxide (SO2). These chemical sensors contain an internal solution that is isolated from the sample solution by an hydrophobic membrane which is permeable to dissolved gas molecules... 

Sensors based on adsorption of species onto or into lattice structures have been reported for molecules besides water. For example, devices based on the detection of carbon dioxide adsorption onto semiconductor materials have been developed [10]. In other cases, dielectric materials that have some degree of chemical specificity have been used for making chemically-sensitive layers. One such application is the use of the highly porous zeolite lattice to detect adsorbed hydrocarbons [11]. The specific dimensions and shape of the zeolite pores allows for size and chemical selectivity in the lattice. As in the case of the humidity devices, the adsorbed molecules dipoles cause a local change in the electric fields that can be detected through a capacitive effect. 

Carbon dioxide is chemically inactive so that some kind of sensors such as the semiconductor sensor is not adequate to detect CO, because the semiconductor sensor operates on the principle based on chemical reaction of gases at the surface. Most of simple and handy sensors are based on the effect of adsorption, desorption and electrochemical reaction. In Table 7, current status of CO, sensors are summarized together with the requirement of environmental monitoring and conventional analytical equipments[6]. Recently, electrochemical sensors, especially solid electrolyte CO, sensors have been actively studied and developed[56-63]. 

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... 

Patel, N. G., Makhija, K. K. and Panchal, C. J. (1994) Fabrication of carbon dioxide gas sensor and its alarm system using indium tin oxide (ITO) thin films. Sensors and Actuators B Chemical 21,193-7. 

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