Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: The purpose of the present invention is to measure pH of a sample with high accuracy in a pH sensor array, without the use of a glass reference electrode. Each time that a sample is measured, the potential Vrm of the sample is identified, and the identified potential Vrm is used to calculate the pH. The outputs Voi1 and Voi2 of a first element and a second element located near one another in a sensor array are represented as follows. Voi1=Si1×pHi1+Gi1×Vrm+Ci1, Voi2=Si2×pHi2+Gi2×Vrm+Ci2. Voi is the output of the element, Si and Gi are sensitivity coefficients, and Ci is a constant, these values having been derived in advance. Here, where the potential Vrm is constant, and the elements located near one another are presumed to be at equal pH (pHi1=pHi2), the potential Vrm is identified by solving a linear equation with two unknowns.

Abstract: Provided is a small-sized device for measuring an oxidation-reduction potential, whereby an oxidation-reduction current and an oxidation-reduction potential can be measured by reducing noise even when a signal from a solution being measured is small. A device for measuring an oxidation-reduction potential is provided with a substrate (10), a working electrode (15) mounted on a surface of the substrate (10), and a bipolar transistor (21) for amplifying the output of the working electrode (15) also provided on the surface of the substrate (10), and the signal amplified by the bipolar transistor (21) is inputted to a processing circuit (18).

Abstract: Contacting a pair of electrodes with soil, applying an alternate current input electric signal to one of the pair of electrodes, comparing a phase of an output electric signal from the other of the pair electrodes with a phase of the input electric signal; and determining the concentration of the ionic solute included in the solvent according to a difference of the phases. The difference of the phases is not dependent on the water content. An electrical conductivity is proportional to a water content and ion concentration, thereby, the water content of soil is available according to the measured electrical conductivity, while determining the ion concentration.

Abstract: The purpose of the present invention is to measure pH of a sample with high accuracy in a pH sensor array, without the use of a glass reference electrode. Each time that a sample is measured, the potential Vrm of the sample is identified, and the identified potential Vrm is used to calculate the pH. The outputs Voi1 and Voi2 of a first element and a second element located near one another in a sensor array are represented as follows. Voi1=Si1×pHi1+Gi1×Vrm+Ci1, Voi2=Si2×pHi2+Gi2×Vrm+Ci2. Voi is the output of the element, Si and Gi are sensitivity coefficients, and Ci is a constant, these values having been derived in advance. Here, where the potential Vrm is constant, and the elements located near one another are presumed to be at equal pH (pHi1=pHi2), the potential Vrm is identified by solving a linear equation with two unknowns.

Abstract: Provided is a small-sized device for measuring an oxidation-reduction potential, whereby an oxidation-reduction current and an oxidation-reduction potential can be measured by reducing noise even when a signal from a solution being measured is small. A device for measuring an oxidation-reduction potential is provided with a substrate (10), a working electrode (15) mounted on a surface of the substrate (10), and a bipolar transistor (21) for amplifying the output of the working electrode (15) also provided on the surface of the substrate (10), and the signal amplified by the bipolar transistor (21) is inputted to a processing circuit (18).

Abstract: Contacting a pair of electrodes with soil, applying an alternate current input electric signal to one of the pair of electrodes, comparing a phase of an output electric signal from the other of the pair electrodes with a phase of the input electric signal; and determining the concentration of the ionic solute included in the solvent according to a difference of the phases. The difference of the phases is not dependent on the water content. An electrical conductivity is proportional to a water content and ion concentration, thereby, the water content of soil is available according to the measured electrical conductivity, while determining the ion concentration.