Carbon monoxide sensor

The first report of a carbon monoxide-sensitive MOSFET was by Dobos et al in 1979 (32), using a palladium-gate MOSFET which was manufactured with holes in the gate electrode (similar to the arsine-sensitive device described above). The initial theory for the sensitivity of the device was that the carbon monoxide molecules were absorbed on to the surface of the palladium metal (including down the holes). The carbon monoxide molecules near the bare gate insulator then affected the field experienced by the devices because of the inherent dipole moment on carbon monoxide. 

Further reports by Dobos et al (33,34) confirmed the initial results, but also showed that the response of the device was variable, depending on its previous history. The authors predicted a response characteristics of the device based on a Langmuir type of adsorption of the carbon monoxide on to the palladium surface  

A different carbon monoxide-sensitive MOSFET in which the gate contact was made from tin dioxide was described by Dobos et al (34). This device sensed the gas by a change in the Fermi energy of the tin dioxide on adsorption of carbon monoxide. The device was shown to respond well to carbon monoxide, but had poor baseline stability, due to the poorly conducting nature of the tin dioxide required for high gas sensitivity. 

Several types of gas-sensitive MOS devices have been developed since 1975. Already sensors for hydrogen, ammonia, hydrogen sulphide, ethanol vapour, arsine and carbon monoxide have been developed. The devices have the 

Lundstrom, S. Shivaraman, C. Svensson and L. Lundkvist, Appl. Phys. Lett. 26 (1975) 55-57. 

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Sachse, G. W., G. F. Hill, L. O. Wade, and M. G. Perry, Fast-Response, High-Precision Carbon Monoxide Sensor Using a Tunable Diode Laser Absorption Technique, J. Geophys. Res., 92, 2071-2081 (1987). 

Carbon monoxide sensor. Carbon monoxide is a toxic air pollutant originating from incomplete combustion of fuels in burners or engines. Despite a strong demand for a very reliable carbon monoxide sensor, the only available sensor was based on an electrochemical type until recently. In this type sensor, selectivity and sensitivity for CO can often be enhanced by selecting elecrode materials and electrode potential appropriately, but several disadvantages are encountered, such as, short life, difficult maintenance and a rather expensive price. 

It is also essential to know the cross-sensitivity of the zirconia single-crystal sensors to other gases. Sensors with porous Pt electrodes are known to be sensitive to gases such as CO at low temperatures [41], and in fact, this cross-sensitivity has been proposed as a principle for carbon monoxide sensors at low temperatures by some researchers [42, 43]. This effect is attributed to the ability of CO to compete successfully with oxygen for adsorption sites on Pt at temperatures from 500°C to 650°C. It was observed that the zirconia single-crystal sensor with thin-film Pt-Zr02-Y2O3 electrodes is less sensitive to CO than similar polycrystalhne sensors with porous Pt electrodes, but small em/errors still occur at 300-360°C. 

Albery et al. (1987a) developed a carbon monoxide sensor based on the sequence of cytochrome oxidase and cytochrome c coupled to a modified gold electrode. The inhibition by CO was detected via the decrease of the oxygen reduction rate. The sensor is also applicable to the quantitation of other inhibitors of the respiratory chain. 

Otagawa T, Madou M, Wing S, Rich-Alexander J, Kusanagi S, Fujioka T and Yasuda A 1990 Planar microelectrochemical carbon monoxide sensors Sensors Actuators B 1 319-25... 

A. Yasuda, K. Doi, N. Yamaga and S. Kusanagi, Electrochemical characteristics of the planar electrochemical carbon monoxide sensor with a perfluorocarbon ionomer film, Solid State Ionics, 1990, 40/41, 476 A. Yasuda, K. Doi, N. Yamaga, T. Fujioka and... 

S. Kusanagi, Mechanism of the sensitivity of the planar CO sensor and its dependency on humidity, J. Electrochem. Soc., 1992, 139, 3224-3229 S.B. Lee, A. Cocco, D. Keyvani and G.J. Maclay, Humidity dependence of carbon monoxide rate in a Nation-based electrochemical cell, J. Electrochem. Soc., 1995, 142, 157-160 R.J. Mortimer and A. Beech, AC impedance characteristics of solid-state planar electrochemical carbon monoxide sensors with Nation as solid polymer electrolyte, Electrochim. Acta, 2002, 47, 3383-3387. 

IV.D.22 Carbon Monoxide Sensors For Reformate Powered Fuel Cells... 

Amperometric low temperature carbon monoxide sensors have been developed and tested under a variety of conditions. These devices respond well at ambient temperature to carbon monoxide in hydrogen streams. 

Low temperature carbon monoxide sensors based on the reversible carbon monoxide adsorptive poisoning of precious metal electrodes are also being developed by Los Alamos National Laboratory. The addition of metals such as ruthenium to the platinum electrode material greatly improves the hydrogen oxidation kinetics in the presence of CO. An amperometric sensor that senses the CO inhibition of the hydrogen oxidation can be fabricated from a platinum electrode, a proton conductor and a platinum ruthenium alloy electrode. While the... 

Turner, A. P. F. Aston, W. J. Higgins, I. J. Bell, J. M. Colby, J. Davis, G. Hill, H. A. O. Carbon-monoxide—acceptor oxidoreductase from pseudomonas-thermocarboxydovorans strain- 2 and its use in a carbon-monoxide sensor. Anal. Chim. Acta 1984, 163, 161-174. 

Aroutionian, V. Metal oxide hydrogen, oxygen, and carbon monoxide sensors for hydrogen setups and cells , (2007) Int J. Hydrogen Energy,32,1145-58. 

Naisbitt, S. C., Pratt,K. F. E., WiUiams, D. E. and Parkin, I. P. (2006) A microstmctural model of semiconducting gas sensor response The effects of sintering temperature on the response of chromium titanate (CTO) to carbon monoxide. Sensors and Actuators B-Chemical 114,969-77. 

Tischner, A., Maier, T, Stepper, C. and Kock, A. (2008) Ultrathin Sn02 gas sensors fabricated by spray pyrolysis for the detection of humidity and carbon monoxide. Sensors and Actuators B Chemical 134,796-802. 

This section analyzes electrochemical sensors for CO2 detection. The two main categories of electrochemical sensing principles are reviewed (amper-ometric and potentiometric) and among potentiometric sensors, special attention is given to mixed potential sensors, because carbon monoxide sensors belong to this group. The influence of the materials and fabrication processes in the sensor performance is also evaluated. 

In the following section novel approaches to improve the performance of carbon monoxide sensors are reviewed. Firstly, photoactivation in metal oxide semiconductors is analyzed and secondly, the new possibilities open the use of nanostructured materials in this field is studied. 

Experimental apparatus Electromagnetic emission source, electromagnetic energy meter (tesla), high frequency mechanical wave recorder, coal and rock strain recorder, methane, ethane, carbon monoxide sensors, data logger. 

Santhosh, R, Manesh, K. M., Gopalan, A., and Lee, K. P. (2007). Novel amperometric carbon monoxide sensor based on multi-wall carbon nanotubes grafted with polydiphenylamine-Fabrlcatlon and performance. Sens. Actuators B, 125, pp. 92-99. 

Thermal evaporation of PANI has been also developed to fabricate PANI thin film by vacuum deposition of PANI powder on the reference electrode [310]. The chemically synthesized PANI powder was formed in pellet type and the pelletized PANI was evaporated on glass substrates at a pressure of 10 mm Hg to form PANI thin film. The pre-cleaned glass substrate was covered uniformly with PANI thin film and this thin film was utihzed as a carbon monoxide sensor. Thus, thermal evaporation method could be used for thin film formation of conducting polymer nanomaterials [311-313]. 

Santhosh P, Manesh KM, Gopalan A, Lee K-P (2007) Novel amperometric carbon monoxide sensor based on multi-wedl carbon nanotubes grafted with polydiphenylamine-fabrication and performance. Sens Actuators B 125 92-99 Shai K, Wagner J (1982) Enhanced ionic conduction in dispersed solid electrolyte systems (DSES) and/or multiphase systems Agl-Al Oj, Agl-SiO, Agl-Ely ash, and Agl-AgBr. J Sohd State Chem 42 107-119 Shimizu Y, Yamashita N (2000) Solid electrolyte CO sensor using NASICON and perovskite-type oxide electrode. Sens Actuators B 64 102-106... 

Lampe U, GerbUnger J, Meixner H (1995a) Carbon-monoxide sensors based on thin films of BaSnO. Sens Actuators B 24-25 657-660... 

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