The disclosure describes techniques to damp the proof mass motion of an accelerometer while achieving an underdamped resonator. In an example of an in-plane micro-electromechanical systems (MEMS) VBA, the proof mass may contain one or more damping combs that include one or more banks of rotor comb fingers attached to the proof mass. The rotor comb fingers may be interdigitated with stator comb fingers that are attached to fixed geometry. These damping comb fingers may provide air damping for the proof mass when the MEMS die is placed into a package containing a pressure above a vacuum. The geometry of the damping combs with a reduced air gap and large overlap area between the rotor comb fingers and stator comb fingers. The geometry of resonator of the VBA of this disclosure may be configured to avoid air damping.

A piezoelectric sensing module includes a polyvinylidene fluoride (PVDF) piezoelectric film, a first electrode layer that includes multiple receiver electrodes arranged in a first pattern enabling a sensing of a position of an input object on a touch surface using the PVDF piezoelectric film, and a second electrode layer that includes at least one common electrode. The PVDF piezoelectric film is arranged between the first electrode layer and the second electrode layer, with the second electrode layer between the PVDF piezoelectric film and the touch surface.

Provided are mechanically adaptive materials that include a composite gel that is responsive to input energy. In some embodiments, input vibrational energy results in strengthening the composite gel. The strengthening may be reversible or irreversible according to various embodiments. In some embodiments, input vibrational energy generates chemical promotors for cross-linking reactions and/or linear polymerization via mechano-chemical transducers. In some embodiments, an applied shear stress is used to control charge generation and generate chemical promoters for cross-linking and/or linear polymerization. In some embodiments, the composite gels include a polymer network and/or polymer network precursors, reactive groups and/or linkers formed by reaction of the reactive groups, and a mechano-chemical transducer. Also provided are methods of mechanically promoted synthesis of polymers and polymer gels.

There are provided a method for manufacturing a substrate excellent in heat dissipation with a small loss in radio frequencies with no need of a high temperature process in which a metal impurity is diffused, and a substrate of high thermal conductivity. A composite substrate according to the present invention is a composite substrate having a piezoelectric single crystal substrate, a support substrate, and an intermediate layer provided between the piezoelectric single crystal substrate and the support substrate. The intermediate layer is a film formed of an inorganic material, and at least a part of the film is thermally synthesized silica. The intermediate layer may be separated into at least two layers along the bonding surface of the composite substrate. The first intermediate layer in contact with the support substrate may be a layer including thermally synthesized silica.

There is provided a piezoelectric stack, including: a substrate; an electrode film; and a piezoelectric film which is comprised of alkali niobium oxide of a perovskite structure represented by a composition formula of (K.sub.1-xNa.sub.x)NbO.sub.3 (0<x<1), wherein the piezoelectric film comprises crystals having a grain size with a standard deviation of 0.42 μm or less.

A method for fabricating a multi-cell electroacoustic transducer comprises placing a rail layer onto a base, the rail layer comprising a plurality of apertures arranged in an array, filling cavities in the rail layer with a polymer, and applying a flexural plate to the rail layer. The transducer achieves high transmission sensitivity across a broad bandwidth. The transducer may be designed to have a broad or a focused directivity pattern, or may be multi-frequency, depending on the particular application and has a range of applications.

A system for cooling a mobile phone and method for using the system are described. The system includes an active piezoelectric cooling system, a controller and an interface. The active piezoelectric cooling system is configured to be disposed in a rear portion of the mobile phone distal from a front screen of the mobile phone. The controller is configured to activate the active piezoelectric cooling system in response to heat generated by heat-generating structures of the mobile phone. The interface is configured to receive power from a mobile phone power source when the active piezoelectric cooling system is activated.

An electroacoustic transducer 400 is described. The electroacoustic transducer 400 comprises an active element 410. The electroacoustic transducer 400 comprises an acoustic coupling layer 430 arranged to acoustically couple, in use, the active element 410 to a transmission medium. The electroacoustic transducer 400 further comprises a cavity 420 arranged between the active element 410 and the acoustic coupling layer 430 to receive a fluid. In this way, acoustic coupling of the electroacoustic transducer 400 and the transmission medium is improved.

An electroacoustic transducer 400 is described. The electroacoustic transducer 400 comprises an active element 410. The electroacoustic transducer 400 comprises an acoustic coupling layer 430 arranged to acoustically couple, in use, the active element 410 to a transmission medium. The electroacoustic transducer 400 further comprises a cavity 420 arranged between the active element 410 and the acoustic coupling layer 430 to receive a fluid. In this way, acoustic coupling of the electroacoustic transducer 400 and the transmission medium is improved.

A hybrid structure for a surface acoustic wave device comprises a useful layer of piezoelectric material having a first free surface and a second surface disposed on a support substrate that has a lower coefficient of thermal expansion than that of the useful layer, wherein the useful layer comprises an area of nanocavities.