A displacement sensor having a rectangular shaped elastic member. A piezoelectric element is attached to a first main face of the elastic member. The piezoelectric element has a rectangular-shaped piezoelectric sheet and electrodes on both main faces of the piezoelectric sheet. The piezoelectric sheet is made of poly-L-lactic acid and is at least uniaxially-stretched. The piezoelectric element is attached so that the uniaxial-stretching direction of the piezoelectric sheet is 45° relative to a long-side direction of the elastic member. When the elastic member is bent along the long-side direction, the piezoelectric sheet is stretched along the long-side direction, and the piezoelectric element generates voltage of predetermined level.

A piezoelectric transducer includes beam portions each with a fixed end portion and extending in a direction away from the fixed end portion. A base portion is connected to the fixed end portion of each of the beam portions. The beam portions extends in a same plane, and respective extending directions of at least two beam portions are different from each other. The beam portions each include a single crystal piezoelectric layer having a polarization axis in a same direction, an upper electrode layer, and a lower electrode layer. A polarization axis has a polarization component in the plane. An axial direction of an orthogonal axis that is orthogonal to the polarization axis and extends in the above-described plane intersects with an extending direction of each of the plurality of beam portions.

A power generation device is provided. A weight may vibrate in one direction as an axial direction in response to an external vibration. A beam may be arranged in at least one side with respect to the weight in the axial direction of the weight, and vibrate together with the weight. A piezoelectric element may be mounted on the beam. A guide may include a hollow guiding a movement of the weight in the axial direction. A stopper may be included in the weight. The stopper may restrict an amount of the movement of the weight in the axial direction within a predetermined amount. A stopper wall may stop the movement of the weight in the axial direction by contacting with the stopper.

A power generation device includes: a first power generation element that vibrates to generate electric power; a second power generation element that is located lower than the first power generation element to vibrate and thereby generates electric power; and a movable element that attracts the first power generation element downward when the movable element is moving downward, and attracts the second power generation element upward when the movable element is moving upward. The first power generation element vibrates as a result of the downward movement of the movable element, and the second power generation element vibrates as a result of the upward movement of the movable element.

The vibrator device includes: a base; a circuit element disposed on the base; a vibrating element disposed to at least partially overlap the circuit element in a plan view; and a support substrate that is disposed between the circuit element and the vibrating element and supports the vibrating element. In addition, the vibrating element has a frequency adjustment portion that performs frequency adjustment by removing at least a part of the vibrating element, and the support substrate includes a base portion that supports the vibrating element, a support portion that supports the base portion, a beam portion that couples the base portion the support portion, and a shielding portion that is connected to the beam portion, overlaps the frequency adjustment portion in a plan view, and has light shielding properties.

A MEMS piezoelectric device includes a monolithic semiconductor body having first and second main surfaces extending parallel to a horizontal plane formed by first and second horizontal axes. A housing cavity is arranged within the monolithic semiconductor body. A membrane is suspended above the housing cavity at the first main surface. A piezoelectric material layer is arranged above a first surface of the membrane with a proof mass coupled to a second surface, opposite to the first surface, along the vertical axis. An electrode arrangement is provided in contact with the piezoelectric material layer. The proof mass causes deformation of the piezoelectric material layer in response to environmental mechanical vibrations. The proof mass is coupled to the membrane by a connection element arranged, in a central position, between the membrane and the proof mass in the direction of the vertical axis.

A MEMS piezoelectric device includes a monolithic semiconductor body having first and second main surfaces extending parallel to a horizontal plane formed by first and second horizontal axes. A housing cavity is arranged within the monolithic semiconductor body. A membrane is suspended above the housing cavity at the first main surface. A piezoelectric material layer is arranged above a first surface of the membrane with a proof mass coupled to a second surface, opposite to the first surface, along the vertical axis. An electrode arrangement is provided in contact with the piezoelectric material layer. The proof mass causes deformation of the piezoelectric material layer in response to environmental mechanical vibrations. The proof mass is coupled to the membrane by a connection element arranged, in a central position, between the membrane and the proof mass in the direction of the vertical axis.

In one embodiment, a flexural wave absorption system includes a base member connected to a beam that may be subject to flexural waves, an arm member, connected to the base, disposed substantially in parallel alignment with the beam, a mass member connected to a distal end of the arm member, a piezoelectric patch, connected to the arm member, that generates electricity in response to a flexural wave propagating through the beam, and a shunting circuit, connected to the piezoelectric patch, that dissipates electricity generated by the piezoelectric patch to absorb the flexural wave.

Proposed is a self-resonance tuning piezoelectric energy harvester with broadband frequency, including: a piezoelectric beam which is extended along a horizontal direction; a fixing member which fixes opposite ends of the piezoelectric beam; and a mobile mass which the piezoelectric beam passes through, and which is capable of self-movement along the piezoelectric beam through a through-hole which has a free space in addition to a space which the piezoelectric beam passes through, wherein as the mobile mass moves to a position of the piezoelectric beam, generated displacement of a piezoelectric beam is increased, and as the generated displacement becomes greater than the free space, the mobile mass is fixed to a position of a piezoelectric beam at which resonance will occur.

Proposed is a self-resonance tuning piezoelectric energy harvester with broadband frequency, including: a piezoelectric beam which is extended along a horizontal direction; a fixing member which fixes opposite ends of the piezoelectric beam; and a mobile mass which the piezoelectric beam passes through, and which is capable of self-movement along the piezoelectric beam through a through-hole which has a free space in addition to a space which the piezoelectric beam passes through, wherein as the mobile mass moves to a position of the piezoelectric beam, generated displacement of a piezoelectric beam is increased, and as the generated displacement becomes greater than the free space, the mobile mass is fixed to a position of a piezoelectric beam at which resonance will occur.