Abstract: The present invention aims to simplify the structure and a fabrication method of an ion-selective electrode in an ion concentration measuring device that measures an anion, particularly a chloride ion, in a biological component. To this end, in a potential difference measuring unit, a quaternary ammonium salt derivative serving as a ligand for an anion is immobilized to the surface of a gold electrode by using as a linker an insulative molecule forming a self-assembled monolayer. The potential difference measuring unit measures an electromotive force generated with anion binding, as an interface potential change on the surface of the gold electrode. In order to reduce the influence of adsorption of impurities on the electrode surface, a high-molecular weight polymer is physically adsorbed on the gold electrode and thus used when a biological component is measured.

Abstract: Provided are a device, whereby cells, a bacterium or a virus can be quantified in a single unit, an assay system and an assay method. A subject to be assayed such as cells, a bacterium or a virus, which are present on a sensor, can be quantified by using a sensor equipped with multiple electrodes, said electrodes being similar in size to the subject to be assayed, detecting, concerning each electrode, the presence or absence of the subject in the vicinity of the electrode, and adding up the electrodes in which the subject is detected.

Abstract: A crown ether derivative that acts as cation capturing ligand and alkanethiol having a longer carbon chain than a linker are immobilized, coexisting together, on the surface of a gold electrode, by using as the linker an insulating molecule (e.g., alkanethiol) that forms self-assembled monolayers. Electromotive force produced in association with cation coordination is measured by a potentiometer through a change in interfacial potential on the surface of the gold electrode. Further, an insulated gate field effect transistor formed on the same substrate as the gold electrode is used as the potentiometer. Furthermore, a straight-chain polymer physically adsorbed on the gold electrode is used in order to reduce the influence of the adsorption of impurities on the surface of the electrode during biological sample measurement.

Abstract: A potentiometric sensor with suppressed leak current on the surface of an electrode and improved for a dynamic range and a response speed, in which a redox compound is immobilized through insulative molecules on the surface of a gold electrode, and a current between a source and drain of an insulated gate field-effect transistor along with reaction between an oxidized substance or a reduced substance produced by the reaction of a measured substance in a sample solution injector for supplying the sample solution containing the measured substance and an enzyme and a redox compound on the surface of the gold electrode, is monitored on real time to measure the change of the surface potential.

Abstract: Disclosed is a DNA analysis method and a DNA analyzer whose signal intensity is not lowered even when a material at a higher density is measured. There is supplied dATP, dTTP, dGTP, or dCTP from a dATP solution vessel, a dTTP solution vessel, a dGTP solution vessel, or a dCTP solution vessel, and this causes an extension reaction of a double-stranded DNA immobilized to a bead, to yield pyrophosphoric acid. The pyrophosphoric acid is converted into a redox compound by the actions of a reagent and an enzyme contained in a reaction buffer in a reaction buffer vessel. The redox compound causes a variation in surface potential of a measuring electrode bearing an electrochemically active material immobilized thereto through an insulating molecule, and this variation causes a variation in drain current of a field-effect transistor electrically connected to the measuring electrode. Thus, the extension reaction is detected.

Abstract: A potentiometric sensor with suppressed leak current on the surface of an electrode and improved for a dynamic range and a response speed, in which a redox compound is immobilized through insulative molecules on the surface of a gold electrode, and a current between a source and drain of an insulated gate field-effect transistor along with reaction between an oxidized substance or a reduced substance produced by the reaction of a measured substance in a sample solution injector for supplying the sample solution containing the measured substance and an enzyme and a redox compound on the surface of the gold electrode, is monitored on real time to measure the change of the surface potential.

Abstract: It is an object of this invention to measure small amounts of a plurality of sample solutions at the same time. The small amounts of sample solutions are respectively placed on measuring electrodes, a medium is placed across the plurality of sample solutions, a liquid joint of a reference electrode is brought into contact with the medium, and a potential difference between each of the measuring electrodes and the reference electrode via the medium is measured.

Abstract: Disclosed is a DNA analysis method and a DNA analyzer whose signal intensity is not lowered even when a material at a higher density is measured. There is supplied dATP, dTTP, dGTP, or dCTP from a dATP solution vessel, a dTTP solution vessel, a dGTP solution vessel, or a dCTP solution vessel, and this causes an extension reaction of a double-stranded DNA immobilized to a bead, to yield pyrophosphoric acid. The pyrophosphoric acid is converted into a redox compound by the actions of a reagent and an enzyme contained in a reaction buffer in a reaction buffer vessel. The redox compound causes a variation in surface potential of a measuring electrode bearing an electrochemically active material immobilized thereto through an insulating molecule, and this variation causes a variation in drain current of a field-effect transistor electrically connected to the measuring electrode. Thus, the extension reaction is detected.

Abstract: Provided is a potentiometric sensor chip in which the positional relationship among a reference electrode, a measurement electrode, and a sample inlet which enables measurement from the start of a reaction is defined, and further provided is a method for detecting the start time of the reaction. A very small amount of sample is measured with high accuracy. The very small quantity of sample is measured by a rate assay. When a reference electrode (103) is disposed between a sample inlet (102) and a measurement electrode (104), a sample solution arrives at the reference electrode (103) earlier than at the measurement electrode (104), whereby the surface potential of the measurement electrode (104) can be measured simultaneously when the sample solution arrives at the measurement electrode (104) and dissolves a reagent and thereby a reaction starts.

Abstract: Disclosed is a DNA analysis method and a DNA analyzer whose signal intensity is not lowered even when a material at a higher density is measured. There is supplied dATP, dTTP, dGTP, or dCTP from a dATP solution vessel, a dTTP solution vessel, a dGTP solution vessel, or a dCTP solution vessel, and this causes an extension reaction of a double-stranded DNA immobilized to a bead, to yield pyrophosphoric acid. The pyrophosphoric acid is converted into a redox compound by the actions of a reagent and an enzyme contained in a reaction buffer in a reaction buffer vessel. The redox compound causes a variation in surface potential of a measuring electrode bearing an electrochemically active material immobilized thereto through an insulating molecule, and this variation causes a variation in drain current of a field-effect transistor electrically connected to the measuring electrode. Thus, the extension reaction is detected.

Abstract: With an insulated gate field effect transistor in which deoxyribonucleic acid (DNA) probes are immobilized on a gold electrode, extension reaction on the gold electrode is performed with DNA polymerase to directly measure an increased amount of a phosphate group caused by the extension reaction, that is, negative charge, by means of a current change between a source and a drain of the insulated gate field effect transistor. Thus, presence/absence of hybridization of target DNAs with the DNA probes, and presence/absence of the extension reaction are detected. Optimum immobilization density of the DNA probes on the gold electrode is set at 4×1012 molecules/cm2. To reduce surface potential fluctuation caused by external variation (influences of foreign substances), which is a problem when using the gold electrode in a solution, a high-frequency voltage equal to or above 1 kHz is applied between the gold electrode and a reference electrode by a power source.

Abstract: With an insulated gate field effect transistor in which deoxyribonucleic acid (DNA) probes are immobilized on a gold electrode, extension reaction on the gold electrode is performed with DNA polymerase to directly measure an increased amount of a phosphate group caused by the extension reaction, that is, negative charge, by means of a current change between a source and a drain of the insulated gate field effect transistor. Thus, presence/absence of hybridization of target DNAs with the DNA probes, and presence/absence of the extension reaction are detected. Optimum immobilization density of the DNA probes on the gold electrode is set at 4×1012 molecules/cm2. To reduce surface potential fluctuation caused by external variation (influences of foreign substances), which is a problem when using the gold electrode in a solution, a high-frequency voltage equal to or above 1 kHz is applied between the gold electrode and a reference electrode by a power source.

Abstract: Disclosed is a DNA analysis method and a DNA analyzer whose signal intensity is not lowered even when a material at a higher density is measured. There is supplied dATP, dTTP, dGTP, or dCTP from a dATP solution vessel, a dTTP solution vessel, a dGTP solution vessel, or a dCTP solution vessel, and this causes an extension reaction of a double-stranded DNA immobilized to a bead, to yield pyrophosphoric acid. The pyrophosphoric acid is converted into a redox compound by the actions of a reagent and an enzyme contained in a reaction buffer in a reaction buffer vessel. The redox compound causes a variation in surface potential of a measuring electrode bearing an electrochemically active material immobilized thereto through an insulating molecule, and this variation causes a variation in drain current of a field-effect transistor electrically connected to the measuring electrode. Thus, the extension reaction is detected.

Abstract: The present invention aims to simplify the structure and a fabrication method of an ion-selective electrode in an ion concentration measuring device that measures an anion, particularly a chloride ion, in a biological component. To this end, in a potential difference measuring unit, a quaternary ammonium salt derivative serving as a ligand for an anion is immobilized to the surface of a gold electrode by using as a linker an insulative molecule forming a self-assembled monolayer. The potential difference measuring unit measures an electromotive force generated with anion binding, as an interface potential change on the surface of the gold electrode. In order to reduce the influence of adsorption of impurities on the electrode surface, a high-molecular weight polymer is physically adsorbed on the gold electrode and thus used when a biological component is measured.

Abstract: The present invention provides a DNA sequencer using a FET sensor, capable of long-base decoding. Target DNAs are immobilized on the surfaces of spherical fine particles, the fine particles are disposed in the vicinity of metal electrodes each of which is connected electrically to a corresponding one of conductive wirings of the FET sensor and partly has a spherical surface capable of contacting with the fine particles, and the FET sensor detects a change in interfacial potential incident to an extension reaction of DNA molecules containing a hybridization of the target DNA and probe DNA.

Abstract: It is an object of this invention to measure small amounts of a plurality of sample solutions at the same time. The small amounts of sample solutions are respectively placed on measuring electrodes, a medium is placed across the plurality of sample solutions, a liquid joint of a reference electrode is brought into contact with the medium, and a potential difference between each of the measuring electrodes and the reference electrode via the medium is measured.

Abstract: A crown ether derivative that acts as cation capturing ligand and alkanethiol having a longer carbon chain than a linker are immobilized, coexisting together, on the surface of a gold electrode, by using as the linker an insulating molecule (e.g., alkanethiol) that forms self-assembled monolayers. Electromotive force produced in association with cation coordination is measured by a potentiometer through a change in interfacial potential on the surface of the gold electrode. Further, an insulated gate field effect transistor formed on the same substrate as the gold electrode is used as the potentiometer. Furthermore, a straight-chain polymer physically adsorbed on the gold electrode is used in order to reduce the influence of the adsorption of impurities on the surface of the electrode during biological sample measurement.

Abstract: A potentiometric sensor with suppressed leak current on the surface of an electrode and improved for a dynamic range and a response speed, in which a redox compound is immobilized through insulative molecules on the surface of a gold electrode, and a current between a source and drain of an insulated gate field-effect transistor along with reaction between an oxidized substance or a reduced substance produced by the reaction of a measured substance in a sample solution injector for supplying the sample solution containing the measured substance and an enzyme and a redox compound on the surface of the gold electrode, is monitored on real time to measure the change of the surface potential.

Abstract: The production amount of thiol compounds which is the product of the cyclic reaction of enzyme-labeled antibody, or the production rate thereof is measured as an adsorption rate on a gold electrode formed on an insulated gate field-effect transistor. The adsorption rate is measured by monitoring in real time the change in a potential on the gold electrode associated with the formation of a self-assembled monolayer on the gold electrode, that is, the current between a source and a drain in the insulated gate field-effect transistor. The measured adsorption rate is recorded by using a signal processing circuit and a data processing unit. Then, the amount of antigen is found from the adsorption rate. During this measuring, a high frequency voltage is applied to a reference electrode from a power supply to reduce the effect of external variations of the measurement.

Abstract: With an insulated gate field effect transistor in which deoxyribonucleic acid (DNA) probes are immobilized on a gold electrode, extension reaction on the gold electrode is performed with DNA polymerase to directly measure an increased amount of a phosphate group caused by the extension reaction, that is, negative charge, by means of a current change between a source and a drain of the insulated gate field effect transistor. Thus, presence/absence of hybridization of target DNAs with the DNA probes, and presence/absence of the extension reaction are detected. Optimum immobilization density of the DNA probes on the gold electrode is set at 4×1012 molecules/cm2. To reduce surface potential fluctuation caused by external variation (influences of foreign substances), which is a problem when using the gold electrode in a solution, a high-frequency voltage equal to or above 1 kHz is applied between the gold electrode and a reference electrode by a power source.