Shizuoka University

Masato Futagawa

Shoji Kawahito

Keita Yasutomi

Kisho Sakamoto

The soil moisture sensor includes a thermoelectric element disposed in the soil, a first temperature information acquisition unit acquiring a first temperature information that indicates a temporal change in temperature of the soil due to an operation of the thermoelectric element, a second temperature information acquisition unit acquiring a second temperature information that indicates a temporal change in temperature of the soil due to the operation of the thermoelectric element, and an arithmetic device obtaining moisture information on the basis of the temperature information. The arithmetic device includes a gradient information acquisition unit acquiring a temperature change amount per unit time by utilizing the first temperature information and the second temperature information, and a conversion unit converting the temperature change amount into the moisture content by utilizing conversion information indicating a relationship between the temperature change amount and the moisture content.

Moisture sensor

A pH sensor obtains the concentration of measurement ions by being provided in a measurement target containing the measurement ions and non-measurement ions. The pH sensor includes: a measurement target power supply that controls a measurement target voltage of the measurement target; a measurement ISFET that includes a measurement ion sensitive membrane selectively trapping the measurement ions to generate a pH-dependent voltage corresponding to the number of trapped measurement ions; a measurement membrane power supply that controls a membrane control voltage of the measurement ion sensitive membrane; and a power supply control unit that controls the size of a voltage to be output from each of the measurement target power supply and the measurement membrane power supply.

Ion concentration measuring device

A soil sensor includes a current supply unit, an electrode disposed in soil, and a processing unit that obtains a water content and a total ion concentration in the soil. The processing unit includes an information conversion unit that converts a first time and a second time until the measured voltage reaches first threshold voltages and second threshold voltages into frequency information using the temporal change of the measured voltage, an impedance calculation unit that obtains the impedance of the soil, a water content calculation unit that obtains the water content using the impedance, and a total ion concentration calculation unit that obtains the total ion concentration using the impedance.

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Hamamatsu, Japan

Masato Futagawa