Indium oxide thin film based ammonia gas and ethanol vapour sensor
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A sensor for ammonia gas and ethanol vapour has been fabricated using indium oxide thin film as sensing layer and indium tin oxide thin film encapsulated in poly(methyl methacrylate) (PMMA) as a miniature heater. For the fabrication of miniature heater indium tin oxide thin film was grown on special high temperature corning glass substrate by flash evaporation method. Gold was deposited on the film using thermal evaporation technique under high vacuum. The film was then annealed at 700 K for an hour. The thermocouple attached on sensing surface measures the appropriate operating temperature.
The thin film gas sensor for ammonia was operated at different concentrations in the temperature range 323–493 K. At 473 K the sensitivity of the sensor was found to be saturate. The detrimental effect of humidity on ammonia sensing is removed by intermittent periodic heating of the sensor at the two temperatures 323K and 448 K, respectively. The indium oxide ethanol vapour sensor operated at fixed concentration of 400 ppm in the temperature range 293–393 K. Above 373 K, the sensor conductance was found to be saturate. With various thicknesses from 150–300 nm of indium oxide sensor there was no variation in the sensitivity measurements of ethanol vapour. The block diagram of circuits for detecting the ammonia gas and ethanol vapour has been included in this paper.
KeywordsIndium oxide ammonia sensor ethanol vapour sensor PMMA and Au
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- Echigoya J, Kato S and Enoki H 1992J. Mater. Sci. -Mater. Electron. 3168Google Scholar
- Ertl G 1982Chem. and phys. solid surf. (FL: CRC Press) Vol.m Google Scholar
- Girtan M and Rusu G I 1999–2000Analele Stintifice Ale Universitatii, Al. I. Cuza Din Iasi Tomul XLV-XLVIs Fizica Starii Condenstate pp 166–172Google Scholar
- Gopel W 1985Mess. 52 47, 92, 175Google Scholar
- Hamberg H, Granquist C G, Berggen K F, Sernelieus B E and Engstron L 1984Phys. Rev. B30 3240Google Scholar
- Kanefusa S, Nitta M and Harodome M 1983Anal. Chem. Symp. Ser. 17 84Google Scholar
- Kim H, Horwitz J S, Pique A, Gilmore C M and Chrisey D B 1990Appl. Phys. Suppl. Mater. Sci. & Process. A69 S447Google Scholar
- Nelli P and Sberveglieri G 1994 inSensors for domestic applications (eds) Arnaldo D’Amico and Giorgio Sberveglieri(Proceeding of the Ist European school on sensors) (Leece, Italy: Castro Marina)Google Scholar
- Oomman K, Varghese L and Malhotra K 1998Sens. & Act. B53 19Google Scholar
- Radhakrishnan C, Subramanyam T K, Uthanne S and Srinivaala Naidu B 1997Bull. Indian Vac. Soc. 28 17Google Scholar
- Raju H R and Rao C N R 1991Sens. & Act. B3/4 365Google Scholar
- Rao CNR, Raju A R and Vijaymohan K 1992New materials (New Delhi: Narosa Publishing House) Ch. 1, pp 1–37Google Scholar
- Tadashi Takada 1998Sens. & Act. B52 45Google Scholar