Abstract: To provide a piezoelectric sensor in which a first electrode for measurement and a second electrode for reference are provided apart from each other on one surface side of a piezoelectric piece and a common electrode is provided on an opposite surface side so as to face the first and second electrodes. A piezoelectric sensor includes: a first electrode for measurement and a second electrode for reference provided apart from each other on one surface side of a piezoelectric piece; a common electrode provided on an opposite surface side of the piezoelectric piece commonly for the first electrode and the second electrode to face the first electrode and the second electrode; and an adsorption layer formed on an area, of the common electrode, to which the first electrode is faced across the piezoelectric piece, to adsorb a substance to be sensed.

Abstract: An object of the present invention is to improve detecting ability of a piezoelectric sensor.

Abstract: Provided is a piezoelectric resonator having high frequency stability and a sensing sensor using the piezoelectric resonator. A piezoelectric resonator has a first oscillation area which is provided in a piezoelectric piece and from which a first oscillation frequency is taken out. A second oscillation area which is provided in an area different from the first oscillation area via an elastic boundary area and from which a second oscillation frequency is taken out. Excitation electrodes are provided on one surface side and another surface side of the oscillation areas across the piezoelectric piece, and a frequency difference between the first oscillation frequency and the second oscillation frequency is not less than 0.2% nor greater than 2.2% of these oscillation frequencies.

Abstract: To provide a sensing device using a piezoelectric sensor having an oscillation area for detection and an oscillation area for reference and capable of achieving a high measurement sensitivity by improving shapes of excitation electrodes. On a quartz-crystal piece 20a, there are provided strip-shaped left side area and right side area which are formed symmetrically to be separated from each other into left and right with respect to a center of a circle 53 being a contour of a planar shape of a reaction channel 52 and extend in a longitudinal direction in a parallel manner.

Abstract: To provide a sensing device that measures a substance to be sensed while letting a sample solution flow and has improved accuracy in detecting the substance to be sensed. The sensing device includes: a channel forming member 50 including an opposed surface opposed to an oscillation area on one surface side of a piezoelectric sensor via a gap to form a reaction channel in an area facing the one surface side; a liquid supply channel through which a liquid is supplied to the reaction channel and a liquid discharge channel through which a liquid is discharged from the reaction channel; oscillator circuits 30a, 30b oscillating the quartz-crystal piece; and a frequency measuring part 81 measuring oscillation frequencies of the oscillator circuits 30a, 30b, wherein a height of the reaction channel facing the oscillation area on the one surface side of the quartz-crystal sensor is 0.2 mm or less.

Abstract: To provide a piezoelectric sensor in which a first electrode for measurement and a second electrode for reference are provided apart from each other on one surface side of a piezoelectric piece and a common electrode is provided on the other surface side so as to face the first and second electrodes, and which achieves highly reliable oscillation by reducing the influence of electrical coupling between the first electrode and the second electrode. A piezoelectric sensor includes: a first electrode for measurement and a second electrode for reference provided apart from each other on one surface side of a piezoelectric piece; a common electrode provided on the other surface side of the piezoelectric piece commonly for the first electrode and the second electrode to face the first electrode and the second electrode; and an adsorption layer formed on an area, of the common electrode, to which the first electrode is projected, to adsorb a substance to be sensed.