An object is to provide a piezoelectric film with good piezoelectricity. This object can be achieved by a piezoelectric film comprising a vinylidene fluoride/tetrafluoroethylene copolymer film and having a residual polarization amount of 40 mC/m.sup.2 or more.

A mobile device includes one or more piezoelectric polymer layers underlying a display. The one or more piezoelectric polymer layers may be electrically driven to operate in either a d33 stretching mode or a d31 bending mode. The mobile device functions as an ultrasonic sensor in the d33 stretching mode and as an audio speaker/microphone or a proximity sensor in the d31 bending mode. The piezoelectric polymer layer operating in the d31 bending mode may be directly mechanically coupled to a display, indirectly mechanically coupled to the display and underlying an ultrasonic sensor stack, or integrated in the ultrasonic sensor stack. Signal performance of the piezoelectric polymer layer operating in the d31 bending mode may be enhanced or modulated by having a larger area, multiple layers, bi-pole or uni-pole driving with multiple layers, one or more stiff adhesives, a spacer layer, one or more mass features, a thin TFT layer, a thick piezoelectric polymer layer, or combinations thereof.

An ultrasonic sensor includes an adhesion sensor detecting adhesion of a foreign substance to a first surface of a bottom of a microphone housing. The adhesion sensor includes: a plurality of variable capacitances defined between a plurality of sensor electrodes disposed on the first surface of the bottom, each of the variable capacitances having a capacitance value which changes in response to adhesion of a foreign substance to the first surface; and an adhesion detection unit configured to measure an individual capacitance value which is a capacitance value of each of the variable capacitances and a total capacitance value which is a total of capacitance values of all the variable capacitances to determine, based on the individual capacitance value and the total capacitance value, whether a foreign substance adheres to the first surface, and, when it is determined that a foreign substance adheres, specify a type of the foreign sub stance.

The present disclosure relates to a sensor assembly (100) comprising: a base (102) having a host-device interface (104), a lid (108) mounted on the base (102) to form a housing (110), the lid (108) having an insulative structural core (112) between an inner metal skin (114) and an outer metal skin (116); and a transduction element (118) disposed in the housing (112). Advantageously, the lid (108) of the sensor assembly (100) can help to minimize and reduce undesirable thermo-acoustic effects produced by external environmental conditions that may result in acoustic artifacts.

A sensor unit capable of protecting a piezoelectric element and detecting vibration and sound is provided. The sensor unit comprises a sheet-like piezoelectric element having a porous layer, and a sound propagation sheet covering at least one face of the piezoelectric element and permitting transmission of sound from a first face toward a second face of the sound propagation sheet. A difference in acoustic pressure level between the sound incident on the sound propagation sheet and the transmitted sound is preferably no greater than 10 dB. A surface density of the sound propagation sheet is preferably from 0.03 g/m.sup.2 to 100 g/m.sup.2. The sound propagation sheet is preferably flexible and preferably has voids. The sensor unit preferably further comprises a sound insulation sheet covering another face of the piezoelectric element and substantially preventing transmission of sound from a second face toward a first face of the sound insulation sheet.

A transducer, a method of manufacturing a transducer, and a transducing device are provided. The transducer includes a receiving unit and a transmitting unit. The receiving unit includes a first receiving electrode, a first piezoelectric film, and a second receiving electrode which are sequentially stacked, and the receiving unit is configured to convert a first acoustic wave signal into an electrical signal by using a piezoelectric effect of the first piezoelectric film. The transmitting unit is configured to receive a control signal, which is based on the electrical signal, to transmit a second acoustic wave signal.

A micro-electromechanical system (MEMS) device and a method of forming the same, the MEMS device includes a composite substrate, a cavity, a piezoelectric stacking structure and a proof mass. The composite substrate includes a first semiconductor layer, a bonding layer and a second semiconductor layer from bottom to top. The cavity is disposed in the composite substrate, and the cavity is extended from the second semiconductor layer into the first semiconductor layer and not penetrated the first semiconductor layer. The piezoelectric stacking structure is disposed on the composite substrate, with the piezoelectric stacking structure having a suspended region over the cavity. The proof mass is disposed in the cavity to connect to the piezoelectric stacking structure.

The present disclosure is of a bone conduction microphone. The bone conduction microphone comprises of a laminated structure and a base structure. The laminated structure is formed by a vibration unit and an acoustic transducer unit. The base structure is configured to load the laminated structure. At least one side of the laminated structure is physically connected to the base structure. The base structure vibrates based on an external vibration signal, the vibration unit deforms in response to the vibration of the base structure, and the acoustic transducer unit generates an electrical signal based on the deformation of the vibration unit. A resonant frequency of the bone conduction microphone is within a range of 2.5 kHz-4.5 kHz.

A device comprising: a sensor; and a first circuit configured to detect when an input stimulus to the sensor satisfies one or more detection criteria, and further configured to produce a signal upon detection that causes adjustment of performance of the device; and a second circuit for processing input following detection, wherein the second circuit is configured to increase its power level following detection, relative to a power level of the second circuit prior to detection.

Systems and techniques are provided for a piezoelectric transducer. A base plate includes a first electrical contact and a second electrical contact. A transduction element is mounted directly on the base plate and electrically connected to the first electrical contact. A spacer includes a via. The via includes electrically conductive material. The spacer is mounted on the base plate around the transduction element and the electrically conductive material of the via is electrically connected to the second electrical contact. A diaphragm is mounted on the spacer and on the transduction element.