Indium oxide thin film based ammonia gas and ethanol vapour sensor |
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Authors: | K K Makhija Arabinda Ray R M Patel U B Trivedi H N Kapse |
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Affiliation: | (1) Department of Electronics, Sardar Patel University, 388 120 Vallabh Vidyanagar, India;(2) Department of Chemistry, Sardar Patel University, 388 120 Vallabh Vidyanagar, India;(3) Pramukhswami Computer Institute, 388 120 Vallabh Vidyanagar, India |
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Abstract: | 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. |
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Keywords: | Indium oxide ammonia sensor ethanol vapour sensor PMMA and Au |
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