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Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination
Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy
Department of Agricultural, Forest and Food Sciences, Università di Torino, Via Leonardo da Vinci, 44, 10095 Grugliasco, Italy
* Author to whom correspondence should be addressed.
Received: 22 July 2013; in revised form: 21 August 2013 / Accepted: 26 August 2013 / Published: 10 September 2013
Abstract: The aim of this work is to study the sensing behavior of Sr-doped hematite for soil water content measurement. The material was prepared by solid state reaction from commercial hematite and strontium carbonate heat treated at 900 °C. X-Ray diffraction, scanning electron microscopy and mercury intrusion porosimetry were used for microstructural characterization of the synthesized powder. Sensors were then prepared by uniaxially pressing and by screen-printing, on an alumina substrate, the prepared powder and subsequent firing in the 800–1,000 °C range. These sensors were first tested in a laboratory apparatus under humid air and then in an homogenized soil and finally in field. The results evidenced that the screen printed film was able to give a response for a soil matric potential from about 570 kPa, that is to say well below the wilting point in the used soil.
Keywords: hematite; strontium hexaferrite; humidity sensor; soil water content determination
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Tulliani, J.-M.; Baroni, C.; Zavattaro, L.; Grignani, C. Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination. Sensors 2013, 13, 12070-12092.
Tulliani J-M, Baroni C, Zavattaro L, Grignani C. Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination. Sensors. 2013; 13(9):12070-12092.
Tulliani, Jean-Marc; Baroni, Chiara; Zavattaro, Laura; Grignani, Carlo. 2013. "Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination." Sensors 13, no. 9: 12070-12092.