Disclosed is a vibration sensor including a piezoelectric substrate, a first electrode and a second electrode that are arranged on the piezoelectric substrate, an amplifier electrically connected between the first electrode and the second electrode, and a solid medium having a first surface part in contact with the piezoelectric substrate, and a second surface part disposed opposite to the first surface part and used for contact with a target substance, the solid medium having a sound speed lower than the phase speed of a plate wave in the piezoelectric substrate, in which an oscillation loop includes the piezoelectric substrate, the first electrode, the second electrode, the amplifier, and the solid medium, and a vibration of the target substance is detected as a result of variation in the loop length of the oscillation loop in response to the vibration of the target substance.

A piezoelectric element device includes: a substrate including a plurality of vibrating portions having a first vibrating portion and a second vibrating portion; a piezoelectric element group in which a plurality of piezoelectric elements having a first piezoelectric element and a second piezoelectric element provided in the plurality of vibrating portions are coupled in parallel to each other; a plurality of load detectors having a first load detector including the first vibrating portion and the first piezoelectric element provided in the first vibrating portion and a second load detector including the second vibrating portion and the second piezoelectric element provided in the second vibrating portion; and a resin layer covering the piezoelectric element group. The first load detector resonates at a first resonance frequency, the second load detector resonates at a second resonance frequency, the first resonance frequency and the second resonance frequency are different from each other, the first resonance frequency changes in accordance with a load applied to the first load detectors via the resin layer, the second resonance frequency changes in accordance with a load applied to the second load detectors via the resin layer, and a first resonance frequency change range, which are changeable range of the first resonance frequency, and a second resonance frequency change range, which are changeable range of the second resonance frequency, do not overlap each other.

Embodiments of transparent ceramic particles are described. A particle includes an outer shell having an outer surface and an inner surface forming a hollow core; and a response unit housed inside the hollow core.

Aspects of the subject technology relate to an apparatus including a housing, one or more piezoresistive elements and a magnetic actuator. The housing includes a membrane, and the piezoresistive elements are disposed on the membrane to sense a displacement due to a deflection of the membrane. The magnetic actuator is disposed inside a cavity of the housing. The magnetic actuator exerts a repulsive force onto the membrane to reduce the deflection of the membrane.

Provided is a measurement method including measuring, by using a piezoelectric sheet sensor in contact with a measurement object, vibration transmitted from the measurement object to the piezoelectric sheet sensor and measuring pressing force between the measurement object and the piezoelectric sheet sensor.

The present disclosure relates to piezoelectric detection circuits, methods and display devices. A piezoelectric detection circuit is provided that may comprise: a piezoelectric device to convert a pressure into a direct current (DC) signal and to convert a sound wave into an alternating current (AC) signal; a comparison circuit configured to output the direct current signal to a signal processor in a case where the piezoelectric device outputs DC signal, and to output the alternating current signal to the mixer in a case where the piezoelectric device outputs AC signal; the mixer configured to perform a mixing process on the AC signal to generate a mixed signal; and the signal processor configured to process the mixed signal output from the mixer or the direct current signal output from the comparison circuit, to detect the pressure or the sound.

Disclosed is a vibration sensor including a piezoelectric substrate, a first electrode and a second electrode that are arranged on the piezoelectric substrate, an amplifier electrically connected between the first electrode and the second electrode, and a solid medium having a first surface part in contact with the piezoelectric substrate, and a second surface part disposed opposite to the first surface part and used for contact with a target substance, the solid medium having a sound speed lower than the phase speed of a plate wave in the piezoelectric substrate, in which an oscillation loop includes the piezoelectric substrate, the first electrode, the second electrode, the amplifier, and the solid medium, and a vibration of the target substance is detected as a result of variation in the loop length of the oscillation loop in response to the vibration of the target substance.

A force detection sensor includes a base member having a first surface subjected to an external force and a second surface having a normal direction different from the first surface, and electrode fingers placed on the second surface, wherein an arrangement direction of the electrode fingers is different from the normal direction of the first surface in a plan view of the second surface. Further, the second surface includes a surface of a piezoelectric material. A constituent material of the piezoelectric material is quartz crystal. The first surface crosses an electrical axis of the quartz crystal.

A vibration sensor in one aspect of the present invention includes a vibration detection element that has a sheet-shaped piezoelectric element and a pair of electrodes superposed on a front side and a rear side of the piezoelectric element, and a rear surface side gel layer superposed on a side where the vibration detection element faces a surface of a living body.

Embodiments of transparent ceramic particles are described. A particle includes an outer shell having an outer surface and an inner surface forming a hollow core; and a response unit housed inside the hollow core.