An acoustic resonator includes: a resonating unit including a resonating unit including a piezoelectric layer and first and second electrodes disposed on a lower side and an upper side of the piezoelectric layer, respectively; a substrate disposed on a lower side of the resonating unit; a support unit providing a cavity between the substrate and the resonating unit; and an intermediate metal layer separated from the second electrode and disposed in the resonating unit such that at least a portion thereof is surrounded by the piezoelectric layer and the second electrode.

Electroacoustic device (5) for generating at least one acoustic wave (Fv,Vx), the device comprising a piezoelectric substrate (10) and first (15) and second (20) groups of electrodes (60,65,70,75) arranged on the substrate, each electrode of the first and second groups comprising a track (80.sub.a-f,85.sub.a-f,90.sub.a-d,95.sub.a-d), the tracks (90.sub.a-d,95.sub.a-d) of the electrodes of the first group spiralling around a same spiral axis (Z) along a first winding direction (W.sub.1), and the tracks (80.sub.a-f,85.sub.a-f) of the electrodes of the second group spiralling around said spiral axis along a second winding direction (W.sub.2) opposite to the first winding direction.

An electronic device may include a first electrode, a first piezoelectric layer electrically coupled to the first electrode, a first magnetostrictive layer above the first piezoelectric layer, a first tunnel barrier layer above the first magnetostrictive layer, and a ferromagnetic layer above the first ferroelectric layer. The electronic device may further include a second electrode electrically coupled to the ferromagnetic layer a second tunnel barrier layer above the ferromagnetic layer, a second magnetostrictive layer above the second tunnel barrier layer, a second piezoelectric layer above the second magnetostrictive layer, and a third electrode electrically coupled to the second piezoelectric layer. The first piezoelectric layer may be strained responsive to voltage applied across the first and second electrodes, and the second piezoelectric layer may be strained responsive to voltage applied across the second and third electrodes.

An electronic device may include a first electrode, a first piezoelectric layer electrically coupled to the first electrode, a first magnetostrictive layer above the first piezoelectric layer, a first tunnel barrier layer above the first magnetostrictive layer, and a ferromagnetic layer above the first ferroelectric layer. The electronic device may further include a second electrode electrically coupled to the ferromagnetic layer a second tunnel barrier layer above the ferromagnetic layer, a second magnetostrictive layer above the second tunnel barrier layer, a second piezoelectric layer above the second magnetostrictive layer, and a third electrode electrically coupled to the second piezoelectric layer. The first piezoelectric layer may be strained responsive to voltage applied across the first and second electrodes, and the second piezoelectric layer may be strained responsive to voltage applied across the second and third electrodes.

A piezoelectric actuator includes a piezoelectric element having a rectangular shape, a first supporter, and a second supporter. The piezoelectric element includes a pair of main surfaces opposing each other, a first end surface and a second end surface opposing each other in a long side direction of the pair of main surfaces, and a first side surface and a second side surface opposing each other in a short side direction of the pair of main surfaces. The first supporter is provided to be movable according to deformation of the first end surface. The second supporter is provided to be movable according to deformation of the first side surface. The first supporter includes an opposing portion and a protruding portion. The opposing portion opposes the second supporter in the long side direction. The protruding portion protrudes from the opposing portion and abuts on the second supporter.

A piezoelectric actuator includes a piezoelectric element having a rectangular shape, a first supporter, and a second supporter. The piezoelectric element includes a pair of main surfaces opposing each other, a first end surface and a second end surface opposing each other in a long side direction of the pair of main surfaces, and a first side surface and a second side surface opposing each other in a short side direction of the pair of main surfaces. The first supporter is provided to be movable according to deformation of the first end surface. The second supporter is provided to be movable according to deformation of the first side surface. The first supporter includes an opposing portion and a protruding portion. The opposing portion opposes the second supporter in the long side direction. The protruding portion protrudes from the opposing portion and abuts on the second supporter.

An acoustic wave device can have a plurality of coupling portions configured to electrically couple electrodes of the device to the substrate of the device to provide a bypass current pathway through the substrate for heat management. The substrate can be a semiconductor material, which can become more conductive as the temperature increases so that the bypass current pathway diverts more power through the substrate as the temperature increases. The acoustic wave device can be a surface acoustic wave device, which can have an interdigital transducer electrode that has the coupling portions on each of the bus bars and extending through the piezoelectric layer to contact the substrate. The acoustic wave device can be a bulk acoustic wave device in some implementations.

Bulk acoustic wave (BAW) resonators and particularly top electrodes with step arrangements for BAW resonators are disclosed. Top electrodes on piezoelectric layers are disclosed that include a border (BO) region with a dual-step arrangement where an inner step and an outer step are formed with increasing heights toward peripheral edges of the top electrode. Dielectric spacer layers may be provided between the outer steps and the piezoelectric layer. Passivation layers are disclosed that extend over the top electrode either to peripheral edges of the piezoelectric layer or that are inset from peripheral edges of the piezoelectric layer. Piezoelectric layers may be arranged with reduced thickness portions in areas that are uncovered by top electrodes. BAW resonators as disclosed herein are provided with high quality factors and suppression of spurious modes while also providing weakened BO modes that are shifted farther away from passbands of such BAW resonators.

Bulk acoustic wave (BAW) resonators and particularly top electrodes with step arrangements for BAW resonators are disclosed. Top electrodes on piezoelectric layers are disclosed that include a border (BO) region with a dual-step arrangement where an inner step and an outer step are formed with increasing heights toward peripheral edges of the top electrode. Dielectric spacer layers may be provided between the outer steps and the piezoelectric layer. Passivation layers are disclosed that extend over the top electrode either to peripheral edges of the piezoelectric layer or that are inset from peripheral edges of the piezoelectric layer. Piezoelectric layers may be arranged with reduced thickness portions in areas that are uncovered by top electrodes. BAW resonators as disclosed herein are provided with high quality factors and suppression of spurious modes while also providing weakened BO modes that are shifted farther away from passbands of such BAW resonators.

A vehicle brake pad (100) comprising: a support plate (21); a friction pad (20); at least a shear force sensing device; and an electrical circuit configured to collect signals from the shear force sensing device (1); wherein the shear force sensing device (1) comprises: a sheet (2) of piezoelectric material having a first and a second main faces (3, 4) parallel to each other identifying a shear stress direction (S); at least a first digitated reading electrode (5) located on the first main face (3); at least a second digitated reading electrode (6) located on the second main face (4), the first and second reading electrodes (5, 6) having digits (5a, 6a) aligned along a reading direction (R) orthogonal to the stress shear direction (S); at least a first digitated polarizing electrode (7) located on the first main face (3) and interdigitated with the first digitated reading electrode (5); and at least a second digitated polarizing electrode (8) located on the second main face (4) and interdigitated with the second digitated reading electrode (6); and wherein the piezoelectric material has a bulk electric polarization with vector field (E) transversally oriented to the reading direction (R), each pair of aligned digits (5a, 6a) of the first and second reading electrodes (5, 6) enclosing a respective zone (2a) of the piezoelectric material having the