In a piezoelectric element, shift of a resonance point to a low-pitched sound side is achieved. A resonance point of a piezoelectric element moves to a low-pitched sound side when an active region is configured to be surrounded by an inactive region as in the configuration of the piezoelectric element. According to the piezoelectric element whose resonance point is moved to a low-pitched sound side, the piezoelectric element can realize a sound pressure that is sufficiently high for practical use when it is applied to an acoustic device.

A piezoelectric cooling system and method for driving the cooling system are described. The piezoelectric cooling system includes a first piezoelectric cooling element and a second piezoelectric cooling element. The first piezoelectric cooling element is configured to direct a fluid toward a surface of a heat-generating structure. The second piezoelectric cooling element is configured to direct the fluid to an outlet area after heat has been transferred to the fluid by the heat-generating structure.

A field-driven electroactive polymer actuator is provided with a current sensor for sensing a current flowing to the actuator. A control circuit is used for driving the actuator which includes a voltage source. The driving of the actuator is controlled in dependence on the sensed current, thereby to provide a predetermined charge delivery for particular changes in actuation level of the actuator. This provides a combined voltage-based and current-based drive scheme for a voltage-driven EAP actuator, and it enables mechanical movements of the actuator to be more reliably repeated.

An optical transformer includes a light source and an array of photovoltaic cells optically coupled to the light source, where at least a portion of the photovoltaic cells are connected in series. An optical connector such as a waveguide or an optical fiber may be disposed between an output of the light source and an input of the array of photovoltaic cells. Configured to generate a high voltage output, the optical transformer may be configured to power a device such as an actuator that provides a tunable displacement as a function of voltage.

A cooling system and method for using the cooling system are described. The cooling system includes a plurality of individual piezoelectric cooling elements spatially arranged in an array extending in at least two dimensions, a communications interface and driving circuitry. The communications interface is associated with the individual piezoelectric cooling elements such that selected individual piezoelectric cooling elements within the array can be activated based at least in part on heat energy generated in the vicinity of the selected individual piezoelectric cooling elements. The driving circuitry is associated with the individual piezoelectric cooling elements and is configured to drive the selected individual piezoelectric cooling elements.

A movable piezo element and to a method for producing the element are provided. The movable piezo element may have a structured substrate, in which an intermediate layer is arranged between a first substrate layer and a second substrate layer. The element may also have a first electrode layer. The element may also have a second electrode layer arranged on the ferroelectric, piezoelectric, or flexoelectric layer. The second substrate layer may be structured such that at least one bar of the second substrate layer is formed. The bar may be clamped on one side and may be physically spaced from the first substrate layer. A surface of the bar facing away from the first substrate layer, and/or a lateral surface of the bar, may be at least partly covered by another layer.

A vibration generating device 10 includes: a diaphragm 11; and a first piezoelectric actuator 12 and a second piezoelectric actuator 13 attached on an upper surface 11a and a lower surface 11b of the diaphragm 11, respectively, so as to sandwich the diaphragm 11 therebetween in a vicinity of an end surface of the diaphragm 11, wherein, in a top view of the upper surface 11a of the diaphragm 11, the first piezoelectric actuator 12 is disposed at a position shifted with respect to the second piezoelectric actuator 13.

A vibration apparatus can include a first cover member; a second cover member; a vibration portion between the first cover member and the second cover member; a contact portion between the first cover member and the vibration portion; and a signal cable. The signal cable can include a first signal line connected to a first surface of the vibration portion via the contact portion, and a second signal line connected to a second surface of the vibration portion opposite to the first surface of the vibration portion.

A sound apparatus can include a vibration member; a housing at a rear surface of the vibration member; a connection member disposed between the vibration member and the housing; and a vibration apparatus configured to vibrate the vibration member. The vibration apparatus can include at least one piezoelectric element for producing sound. Also, the connection member can have a first stiffness that is less than a second stiffness of the housing, and the vibration member can be isolated from the housing by the connection member.

A piezoelectric device including a substrate, a metal-insulator-metal element, a hydrogen blocking layer, a passivation layer, a first contact terminal and a second contact terminal is provided. The metal-insulator-metal element is disposed on the substrate. The hydrogen blocking layer is disposed on the metal-insulator-metal element. The passivation layer covers the hydrogen blocking layer and the metal-insulator-metal element. The first contact terminal is electrically connected to the metal-insulator-metal element. The second contact terminal is electrically connected to the metal-insulator-metal element.