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Sensors 2002, 2(3), 91-110; doi:10.3390/s20300091
Article
Room Temperature Ammonia and Humidity Sensing Using Highly Ordered Nanoporous Alumina Films
Elizabeth C. Dickey 1,*
, Oomman K. Varghese 1 , Keat G. Ong 2 , Dawei Gong 2 , Maggie Paulose 2 and Craig A. Grimes 2
, Oomman K. Varghese 1 , Keat G. Ong 2 , Dawei Gong 2 , Maggie Paulose 2 and Craig A. Grimes 2
1
Department of Materials Science & Engineering, The Pennsylvania State University, University Park, PA 16802, USA
2
Department of Electrical Engineering & Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
* Author to whom correspondence should be addressed.
Received: 9 February 2002 / Accepted: 1 March 2002 / Published: 18 March 2002
(This article belongs to the Special Issue Nano-Porous Sensor Material)
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Abstract: The effect of pore size and uniformity on the response of nanoporous alumina, formed on aluminum thick films through an anodization process, to ammonia and humidity at room temperature is reported. Pore sizes examined range from 13 nm to 48 nm, with pore size standard deviations ranging from 2.6 nm to 7.8 nm. The response of the material to ammonia and humidity is a strong function of pore size and operating frequency. At 5 kHz an alumina sensor with an average pore size of 13.6 nm, standard deviation 2.6 nm, exhibits a factor of two change in impedance magnitude as it is cycled between an ammonia and argon environment. At 5 kHz the same sensor exhibits a well-behaved change in impedance magnitude of 103 over 20% to 90% relative humidity. Cole-Cole plots of the 5 Hz to 13 MHz measured impedance spectra, modeled using equivalent circuits, are used to resolve the effects of adsorption and ion migration.
Keywords: Ammonia; Nanoporous; Impedance spectroscopy; Alumina; Humidity; Mesoporous
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MDPI and ACS Style
Dickey, E.C.; Varghese, O.K.; Ong, K.G.; Gong, D.; Paulose, M.; Grimes, C.A. Room Temperature Ammonia and Humidity Sensing Using Highly Ordered Nanoporous Alumina Films. Sensors 2002, 2, 91-110.
AMA StyleDickey EC, Varghese OK, Ong KG, Gong D, Paulose M, Grimes CA. Room Temperature Ammonia and Humidity Sensing Using Highly Ordered Nanoporous Alumina Films. Sensors. 2002; 2(3):91-110.
Chicago/Turabian StyleDickey, Elizabeth C.; Varghese, Oomman K.; Ong, Keat G.; Gong, Dawei; Paulose, Maggie; Grimes, Craig A. 2002. "Room Temperature Ammonia and Humidity Sensing Using Highly Ordered Nanoporous Alumina Films." Sensors 2, no. 3: 91-110.