Methods for creating undulating structures are disclosed in which an elastic sheet and a rigid restraining member having different curvatures are joined. The structures incorporate stopping members, such as stopped grooves, to manage the transverse deformations of the elastic sheet. The joint is such that the transverse deformations may migrate along the undulating structure in a coordinated, wave, either to gather kinetic energy, or to propel the structure relative to a fluid. To facilitate such a wave, the elastic sheet can be joined to the retaining member via passive stopping members that oscillate about their points of attachment to the retaining member. These are also constructed to limit the elastic sheet from reverting to its original configuration. The retaining member can be annular structures, and the elastic sheet members can be tubular. Stopping members can be actuated to power the transverse deformations of the elastic sheet to oscillate.

Disclosed is an electronic device. The electronic device according to an embodiment may include an ultrasonic sensor and a processor electrically connected to the ultrasonic sensor. The processor may be configured to obtain a noise signal at a periphery of the electronic device, via the ultrasonic sensor, to determine an attribute of a first ultrasonic signal oscillated by the ultrasonic sensor, based on the obtained noise signal, and to obtain fingerprint information based on the second ultrasonic signal obtained via the ultrasonic sensor and the determined attribute. Moreover, various embodiment found through the disclosure are possible.

A sensor device comprising a two-dimensional array of ultrasonic transducers, wherein the two-dimensional array of ultrasonic transducers is substantially flat, a non-uniform contact layer overlying the two-dimensional array of ultrasonic transducers, and a sensor processor is described. The sensor device is configured to: transmit ultrasonic signals using the two-dimensional array of ultrasonic transducers for reflection from an object in contact with the non-uniform contact layer, wherein the ultrasonic signals traverse the non-uniform contact layer, receive reflected ultrasonic signals at the two-dimensional array of ultrasonic transducers, obtain non-uniformity data characterizing the non-uniform contact layer, control operating parameters of the sensor device based on the non-uniformity data, and generate an image of the object in contact with the non-uniform contact layer based on the reflected ultrasonic signals, wherein the image is corrected for non-uniformity of the non-uniform contact layer.

A piezoelectric micromachined ultrasound transducer (PMUT) device may include a plurality of layers including a structural layer, a piezoelectric layer, and electrode layers located on opposite sides of the piezoelectric layer. Conductive barrier layers may be located between the piezoelectric layer and the electrodes to the prevent diffusion of the piezoelectric layer into the electrode layers.

The invention relates to a seat arranged for enhanced sound perception via vibration including a padding and a sound reproduction assembly (20), which includes at least one vibration source (26), at least one elastic element (16, 21) and at least one frame structure (18, 22), which sound reproduction assembly is at least partially arranged inside the padding. The elastic element/-s (16, 21) are nonhomogenous element/-s and located in contact with the frame structure (18, 22) and the vibration source (26) and configured to provide elastically and mechanically tuned mounting and that the elastic element/-s are configured to create at least lateral vibration to the surface of the seat.

The invention refers to an infrasound generator for enhancing the combustion of solid fuels burning in a combustion chamber. The infrasound is generated by one or more set(-s) of each two vibrating plates, vibrating in the same direction with the same displacement amplitude but in antiphase. The infrasound generator does not cause vibrations and is not sensitive to ash and heat from the combustion.

An amplifier system may include a first feedback loop coupled between an output of an amplifier to an input of a modulator for regulating an output voltage driven at the output of the amplifier to a first terminal of a load of the amplifier system, a sense resistor for sensing a physical quantity associated with the amplifier, a second control loop coupled to the sense resistor such that the sense resistor is outside of the second control loop, the second control loop configured to regulate a common-mode voltage at a second terminal of the load, and a common-mode feedforward circuit coupled to the sense resistor and configured to minimize effects of a signal-dependent common-mode feedback of the sense resistor.

A filtering apparatus formed by a plurality of channel systems. Each of the channel systems include an inlet port formed on an inlet side of the plate; no more than one outlet port formed on an outlet side of the plate; and a channel formed in the plate, the channel coupled to the inlet port and to the outlet port, wherein the ratio of the product of the capture area of the inlet ports of a channel system with the first transmissivity associated with the inlet ports to the product of the capture area of the outlet ports of a channel system with the second transmissivity associated with the outlet ports is greater than one. The channel system is configured to interact with objects of interest on a scale which is smaller than a value several orders of magnitude larger than the mean free path of an object of interest. Some plate embodiments are configured to interact with particles, such as air molecules, water molecules, or aerosols. Other plate embodiments are configured to interact with waves or wavelike particles, such as electrons, photons, phonons or acoustic waves.

A biometric information sensor includes a first substrate and a first sensor electrode disposed on the first substrate. A second sensor electrode is disposed on the first substrate at a same distance from the first substrate as the first sensor electrode. The second sensor electrode is spaced apart from the first sensor electrode. A piezoelectric layer is disposed between the first sensor electrode and the second sensor electrode. A second substrate is disposed on the first sensor electrode, the second sensor electrode, and the piezoelectric layer.

An ultrasonic vibrator driving apparatus applies a sine-waveform alternating voltage as a drive voltage via a conversion circuit to an ultrasonic vibrator that has a unique resonance frequency. A first current detector that detects a first current that flows from the drive voltage generator to the conversion circuit and a second current detector that detects a second current that flows from the conversion circuit to the ultrasonic vibrator are included. A frequency controller performs control on the drive voltage generator to change the frequency of a square-waveform alternating voltage so that the difference between the first current and the second current is reduced or approaches a minimum.