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Title: Fringing Field Capacitance Sensor for Measuring the Moisture Content of Agricultural Commodities

Author
item MCINTOSH, ROBERT - HORIZON TECHNOLOGY GROUP
item Casada, Mark

Submitted to: Institute of Electrical and Electronics Engineers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2007
Publication Date: 3/1/2008
Citation: Mcintosh, R.B., Casada, M. 2008. Fringing Field Capacitance Sensor for Measuring the Moisture Content of Agricultural Commodities. Institute of Electrical and Electronics Engineers. Vol. 8(3):240-247.

Interpretive Summary: A low-cost moisture sensor was designed for measuring moisture content and temperature of agricultural commodities. The capacitive sensor was mounted on the end of hand-held probes and in 1.5 liter canisters and tested in wheat and corn over a range of moisture contents from approximately 1% to 20%. The sensor response was a consistent and sensitive function of the moisture content of grain for these applications. The sensor offers a promising means to determine the moisture content of grain during storage or transportation in cargo holds. The sensor is water-tight and constructed with corrosion resistant materials which allow moisture content and temperature measurements to also be made of industrial materials, chemicals, and fuels. The sensor may also be supported on cables in grain storage bins to acquire continuous, in situ data for stored grain management and the control of aeration and low-temperature drying systems.

Technical Abstract: A capacitive sensor is described for measuring the moisture content (MC) and temperature of agricultural commodities. Sensor performance was characterized by mounting the device on hand-held probes and in 1.5 liter canisters to determine the dielectric constant and MC of wheat and corn. The hand-held probes demonstrated a promising capability to measure the MC of grain transported and temporarily stored in hoppers, truck beds, and cargo holds. The dielectric constant of fluids and alcohol-water mixtures was measured to explore methods for precision sensor calibration. The potential of sensors supported on cables in grain silos and storage bins to acquire in situ data for grain storage management and control of aeration systems is proposed.