Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination

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.

Humidity Sensors Principle, Mechanism, and Fabrication Technologies: A Comprehensive Review

“…Porous ceramic sensors are extensively used in industry and research laboratories. The unique structures of ceramic materials comprising grains, grain boundaries, surface areas and controlled porous microstructures, makes them suitable candidates for electrochemical sensor applications [ 67 , 68 ]. Various humidity sensing mechanisms have been proposed and studied for different dampness-sensitive reported ceramics.…”

Electrospun Nickel Manganite (NiMn2O4) Nanocrystalline Fibers for Humidity and Temperature Sensing

“…In the food industry, besides humidity monitoring in the food production process, humidity sensors can be incorporated as components of intelligent food packaging [ 3 ]. Precision agriculture requires smart humidity sensors as part of a wireless sensor network [ 4 , 5 ], that includes monitoring of plant soil moisture essential for good plant growth [ 6 , 7 ]. Semiconductor materials, especially metal oxides, are widely applied in gas and humidity sensors [ 8 ] and remain the focus of much research [ 9 , 10 ].…”

Structural, morphological and textural properties of iron manganite (FeMnO3) thick films applied for humidity sensing

“…Monitoring air humidity is essential from the viewpoint of detection and control of the ambient humidity [8], while monitoring soil moisture content is very significant during irrigation [9,10]. Many different oxide systems have been investigated and applied in humidity sensing as resistive or capacitive ceramic humidity sensors.…”