An ultrasonic device includes a substrate, a transmitter provided at the substrate and configured to transmit an ultrasonic wave to an object, and a receiver provided at a position different from the transmitter at the substrate and configured to receive an ultrasonic wave reflected by the object. A resonance frequency of the transmitter is higher than a resonance frequency of the receiver. An anti-resonance frequency of the receiver is included in a predetermined frequency band including the resonance frequency of the transmitter.

According to one embodiment, a transducer includes a first electrode, a second electrode, a third electrode, a first piezoelectric portion, and a second piezoelectric portion. A resistor and an inductor are connected to the second electrode. The first piezoelectric portion is provided between the first electrode and the third electrode. The second piezoelectric portion is provided between the second electrode and the third electrode. A ratio of the absolute value of a difference between a first resonant frequency and a second resonant frequency to the first resonant frequency is 0.29 or less. The first resonant frequency is mechanical. The first resonant frequency is of the first piezoelectric portion and the second piezoelectric portion. The second resonant frequency is of a parallel resonant circuit. The parallel resonant circuit includes an electrostatic capacitance, the inductor, and the resistor. The electrostatic capacitance is between the second electrode and the third electrode.

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.

A method is provided for measuring a flow rate of a fluid. The method incudes emitting a periodic signal from a first ultrasonic transductor, where the periodic signal is emitted by the piezoelectric wafer and passes through a liquid media. Unwanted reflections of the periodic signal are delayed so that the first periods of the periodic signal are representatives of the passage measurement. The first periods of the periodic signal are received at a second ultrasonic transductor having a piezoelectric wafer that receives the periodic signal. The flow rate of the fluid is determined by using the first periods of the periodic signal.

The disclosed flexible vibrotactile devices may include a dielectric support material, at least one flexible electroactive element coupled to the dielectric support material, a first conductive electrode material, and a second conductive electrode material. The dielectric support material may include at least one hole therethrough for securing the flexible vibrotactile device to a textile by threading at least one fiber through the at least one hole. Various other related methods and systems are also disclosed.

According to various embodiments, a PMUT device may include a wafer, an active layer including a piezoelectric stack, an intermediate layer having a cavity therein where the intermediate layer is disposed between the wafer and the active layer such that the cavity is adjoining the piezoelectric stack. A via may be formed through the active layer and the intermediate layer to the wafer. A metallic layer may be disposed over the active layer and over surfaces of the via. The intermediate layer may include an interposing material surrounding the cavity, and may further include a sacrificial material surrounding the via. The sacrificial material may be different from the interposing material. The metallic layer may include a first member at least substantially overlapping the piezoelectric stack, a second member extending from the first member to the cavity, and a third member extending into the active layer to contact an electrode therein.

A transducer (140) having a mechanical impedance over an operative frequency range and having a desired power coupling (145) to a load over the operative frequency range comprises a piezoelectric device (141) having a frequency distribution of modes in the operative frequency range; and an overmould (143). The overmould (143) is arranged to surround at least part of the piezoelectric device (141); and the parameters of the overmould (143) are selected to provide a required impedance matching between the mechanical impedance of the transducer (140) and the mechanical impedance of the load. An alternative transducer comprises a mounting means for holding a discrete portion of at least a part of the periphery of the piezoelectric device wherein the parameters of the mounting means are selected to provide a required boundary condition for the periphery of the piezoelectric device whereby the desired power coupling between the transducer and the load is provided.

A unit and a tactile sensation providing apparatus which enable simplification of the assembly process of the apparatus are provided. The unit is provided with an actuator, a first fixing unit fixable to a base, a second fixing unit, and an elastic member configured to couple the first fixing unit and the second fixing unit together. The second fixing unit is fixable to a vibration object and coupled to the actuator.

A sensor pod assembly comprising a gel pad, a gel pad cap, a piezoelectric sensor, a base plate, a base plate support, a wiring harness, a battery, a noise attenuating backing, and a charging component; said gel pad comprising a top and bottom, said bottom having a flat bottom and a concave recess; said flat bottom acoustically contacting said piezoelectric sensor; said piezoelectric sensor secured to a first side of said base plate support, and a second side of said base plate support secured to said base plate, a wiring harness and a battery connected to said base plate, and a charging component having exposed annular rings on the exterior side of said sensor pod assembly; a noise attenuating backing compressing the charging component against the base plate; and a gel pad cap having an outer face and an inner face, said inner face in contact with said base plate support.

An apparatus may include a display panel configured to display an image, a vibration apparatus disposed at a rear surface of the display panel to vibrate the display panel, wherein the vibration apparatus includes a plurality of vibration structures, and a pad member disposed outside or inside the vibration apparatus.