Optical gas sensors

In context with methane detection during offshore oil drilling, another infrared fiber optic methane sensor was reported25. The detector comprises 3 main units a microcomputer-based signal processing and control unit, a nonconducting fiber optic gas sensor, and an optical fiber cable module. The system operates at an absorption line of methane where silica fibers have very low losses. 

This chapter reviews the development of optical gas sensors, starting with an initial emphasis on optical-fibre remoted techniques and finishing with a particular focus on our own group s work on highly selective methods using correlation spectroscopy. This latter section includes extensive theoretical modelling of a correlation spectroscopy method, and compares theory with practice for a CO2 sensor. 

Linear Energy Solubility Relationships (LSERs) are useful in the design of selective layers for mass and optical gas sensors. 

Mizaikoff B et al (1995) Infrared fiber optic gas sensor for chlorofluorohydrocarbons. Vib Spectrosc 8 103-108... 

Molecular Interactions Between Alcohols and Metal Phthalocyanine Thin Films for Optical Gas Sensor Applications... 

Optical gas sensors generally have some characteristics such as a high insulating capacity, independence of electrical noises and operation in safety. Moreover it is possible for them to detect a variety of gases by choosing a gas sensing material. For environmental use of optical sensors, applications for NO , SOj, CO2 and CO are expected. 

Umar A. A., Salleh M. M., and Yahaya M., Self-assembled monolayer of copper(II) meso-tetra(4-sulfanatophenyl) porphyrin as an optical gas sensor. Sens. Actuators B, 101(1-2), 231-235, 2004. 

Vasiliev, A., Pavelko, R. G, Gogish-Klushin, S. Y., Kharitonov, D. Y., Gogish-Klushina, O.S.,Sokolov,A.V.,Pisliakov,A.V.and Samotaev,N.N. (2008), Alumina MEMS platform for impulse semiconductor and IR optic gas sensors . Sens. Actuators 5,132(1), 216-23. 

Tinsley-Bown AM, Canham LT, Hollings M, Anderson MH, Reeves CL, Cox TI, Nicklin S, Squirrell DJ, Perkins E, Hutehinson A, Sailor MJ, Wun A (2000) Tuning the pore size and surface chemistry of porous silicon for immunoassays. Phys Status Solidi A-Appl Res 182 547 Torres-Costa V, Salonen J, Lehto VP, Martin-Palma RJ, Martinez-Duart JM (2008) Passivation of nanostructured sihcon optical devices by thermal carbonization. Micropor Mesopor Mater 111 636 Torres-Costa V, Salonen J, Jalkanen TM, Lehto VP, Martin-Pahna RJ, Martinez-Duart JM (2009) Carbonization of porous sihcon optical gas sensors for enhanced stability and sensitivity. Phys Status Solidi A 206 1306... 

Table 2 Main architectures of porous silicon optical gas sensors since 1990... 

Table 4 provides study examples on up-to-date sensing platforms exploiting porous silicon either electrical or optical gas sensors. 

P Mieroporous p or p type, approx, porosity range 55-75 %, eleetrolyte HF + ethanol Mirrors, microcavity, rugate filter used as optical gas sensor due to large surface area Escorcia-Garcia et al. (2009), Salem et al. (2008)... 

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