The invention relates to a lead-free piezoceramic material based on bismuth sodium titanate (BST) having the following parent composition: x(Bi.sub.0.5Na.sub.0.5)TiO.sub.3-yBaTiO.sub.3-zSrTiO.sub.3 where x+y+z=1 and 0<x<1, 0<y<1, 0≤z≤0.07 or x(Bi.sub.0.5Na.sub.0.5)TiO.sub.3-yBaTiO.sub.3-zCaTiO.sub.3 where x+y+z=1 and 0<x<1, 0<y<1, 0<z≤0.05 or x(Bi.sub.0.5Na.sub.0.5)TiO.sub.3-y(Bi.sub.0.5K.sub.0.5)TiO.sub.3-zBaTiO.sub.3 where x+y+z=1 and 0<x<1, 0<y<1, 0≤z<1, characterized by addition of a phosphorus-containing material in a quantity that gives a phosphorus concentration of from 100 to 2000 ppm in the piezoceramic material.

An electric controlled bi-directional bending actuator with deformability and stiffness tunable capacity is disclosed. The electric controlled bi-directional bending actuator with deformability and stiffness tunable capacity comprises three kinds of functional layers that are electro-deformable layers, electro-variable stiffness layers and flexible electrodes. From up to bottom, they are the first flexible electrodes layer, the first electro-deformable layer, the second flexible electrodes layer, the electro-variable stiffness layer, the third flexible electrode layer, the second electro-deformable layer and the fourth flexible electrode layer. The adjacent layers are glued together. The electro-deformable layer is made from dielectric elastomers. The electro-variable stiffness layer is made from electro-rheological materials, including electro-rheological fluids, electro-rheological gels or electro-rheological elastomers. Compared with the present pneumatic actuators with deformability and stiffness tunable capacity, the invention has such merits as simple structure, precise regulation, quick response, convenient control and insensitive to environmental.

A device including a piezoelectric actuator that can detect the actuation force and provide haptic feedback. The longitudinal extension of the actuator, generated for this purpose, can be reinforced in the desired direction by a deformable metal sheet. The deformable metal sheet is adhered on and has a borehole for pressure equalization.

Provided is a piezoelectric ceramics including crystal grains each including: a first region that is formed of a perovskite-type metal oxide having a crystal structure in which a central element of a unit cell is located at an asymmetrical position; and a second region that is formed of a perovskite-type metal oxide having a crystal structure in which a central element of a unit cell is located at a symmetrical position, and that is present inside the first region, wherein a ratio of a cross-sectional area of the second region to a cross-sectional area of the piezoelectric ceramics is 0.1% or less.

Embodiments relate to a piezoelectric ceramic and methods of making the same that is suitable for use as a high-power piezoelectric ceramic, and in particular a piezoelectric ceramic that exhibits both good hard properties and good soft properties. Embodiments involve generating the piezoelectric ceramic via the combination of chemical modification/doping and/or a texturing method so that the piezoelectric material exhibits a large figure of merit, as well as other hard and soft properties. The chemical modification involves Cu and Mn doping a piezoelectric material composition having a relaxor-lead titanate based ferroelectric structure. The texturing involves templated grain growth (TGG) texturing using a BaTiO.sub.3 (BT) template.

Aspects of the present disclosure describe systems, methods, and structures that scavenge mechanical energy to provide electrical energy to a wearable, where the mechanical energy is scavenged by a bending-strain-based transducer that includes a non-resonant energy harvester. By employing a non-resonant energy harvester that operates in bending mode, more electrical energy can be generated that possible with prior-art energy harvesters. In some embodiments, the output of a bending-strain-based transducer element is used for both energy scavenging and as a sensor signal indicative of a user parameter, such as a step, respiration rate, heart rate, weight and the like. In some embodiments, a transducer element includes a plurality of piezoelectric layers that are electrically connected in parallel to increase the energy and/or power provided by the transducer element.

In a MEMS device in which a first electrode layer, a piezoelectric layer, and a second electrode layer are stacked in this order from a first surface side of a substrate, a first wiring layer is stacked on a second surface on a side opposite to a first surface of the substrate and the first electrode layer and the first wiring layer are connected to each other via a through wiring passing through the substrate.

A piezoelectric MEMS microphone comprising a multi-layer sensor that includes at least one piezoelectric layer between two electrode layers, with the sensor being dimensioned such that it provides a near maximized ratio of output energy to sensor area, as determined by an optimization parameter that accounts for input pressure, bandwidth, and characteristics of the piezoelectric and electrode materials. The sensor can be formed from single or stacked cantilevered beams separated from each other by a small gap, or can be a stress-relieved diaphragm that is formed by deposition onto a silicon substrate, with the diaphragm then being stress relieved by substantial detachment of the diaphragm from the substrate, and then followed by reattachment of the now stress relieved diaphragm.

Aspects of this disclosure relate to a boundary acoustic wave device. The boundary acoustic wave device can include two low acoustic impedance layers, an interdigital transducer electrode, piezoelectric material positioned between the interdigital transducer electrode and each of the two low acoustic impedance layers, and two high acoustic impedance substrates. The two low acoustic impedance layers can be positioned between the two high acoustic impedance substrates. Related acoustic wave filters, multiplexers, radio frequency modules, wireless communication devices, and methods are disclosed.

Aspects of this disclosure relate to a boundary acoustic wave device. The boundary acoustic wave device can include two low acoustic impedance layers, an interdigital transducer electrode, piezoelectric material positioned between the interdigital transducer electrode and each of the two low acoustic impedance layers, and two high acoustic impedance substrates. The two low acoustic impedance layers can be positioned between the two high acoustic impedance substrates. Related acoustic wave filters, multiplexers, radio frequency modules, wireless communication devices, and methods are disclosed.