Toyohashi University of Technology

Masato Futagawa

Kazuaki Sawada

Fumihiro Dasai

Sou Takahashi

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 Voiand Voiof a first element and a second element located near one another in a sensor array are represented as follows. Voi=Si&#xd7;pHi+Gi&#xd7;Vrm+Ci, Voi=Si&#xd7;pHi+Gi&#xd7;Vrm+Ci. 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 (pHi=pHi), the potential Vrm is identified by solving a linear equation with two unknowns.

Method for identifying pH, device for same, and method for identifying ion concentration

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 (), a working electrode () mounted on a surface of the substrate (), and a bipolar transistor () for amplifying the output of the working electrode () also provided on the surface of the substrate (), and the signal amplified by the bipolar transistor () is inputted to a processing circuit ().

Device for measuring oxidation-reduction potential and method for measuring oxidation-reduction potential

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.

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Toyohashi, Japan

Masato Futagawa