An electroacoustic transducer, comprising a piezoelectric part comprising a piezoelectric material having a first acoustical impedance and an acoustical thickness, a substrate part comprising a material having a second acoustical impedance, and an intermediate part comprising a material having a third acoustical impedance and at least partially sandwiched between the piezoelectric part and the substrate part for acoustical communication therewith. The first acoustical impedance and the second acoustical impedance each has a respective value within a range of values for which the value of third acoustical impedance: is an upper limit if said acoustical thickness is less than 0.4Λ, or is a lower limit if said acoustical thickness is greater than 0.4Λ where Λ is an acoustical wavelength in the material of the piezoelectric part.

A transducer is provided, which includes an oscillator and a broadbanded matching circuit. In the oscillator, a peak frequency corresponding to a peak transmission sensitivity may separate from a center frequency in a given bandwidth, and a transmission sensitivity may increase as a frequency separates from the peak frequency with respect to the center frequency. The broadbanded matching circuit may be configured to perform an impedance matching so that the transmission sensitivity of the oscillator at the peak frequency becomes substantially equal to the transmission sensitivity of the oscillator at the center frequency.

Systems and methods for the ultrasonic disruption of biofilm and algae growth on underwater structures utilize an ultrasonic actuator (10) that produces a natural frequency in the ultrasonic range. In some embodiments, the ultrasonic actuator (10) includes one or more piezoelectric transducers (110).

Disclosed is a broadband underwater acoustic transceiver device. The device can be used in particular for positioning, detection, range finding or underwater acoustic communication. The device coaxially combines, within a transceiver device, a Tonpilz transducer and a FFR transducer, the FFR being arranged in front of the transmission face/horn of the Tonpilz transducer. In such a configuration, the Tonpilz horn also acts as reflective tape for the FFR transducer, forming a common tape-horn element. Furthermore, an annular baffle surrounding the Tonpilz pillar creates a Helmholtz cavity for broadening the emission band towards the low frequencies.

A piezoelectric system for ultrasonic thermotherapy and electrotherapy comprises a first piezoelectric element, a proof mass, a second piezoelectric element and an output unit. The proof mass is disposed between the first piezoelectric element and the second piezoelectric element. The first piezoelectric element is powered by a power source to generate oscillation, which is transferred by the proof mass to the second piezoelectric element so as to cause the second piezoelectric element to move and generate power. The output unit comprises a connecting surface and a tip surface. The output unit is electronically connected with the second piezoelectric element, wherein the connecting surface is connected with the first piezoelectric element and the tip surface is formed in a tapered shape. The oscillation from the first piezoelectric element and the power generated by the second piezoelectric element are output through the tip surface.

A low frequency underwater sound source for use in an autonomous underwater vehicle includes a cylindrical body having a front portion, a rear portion, a cylindrical piezo-ceramic ring transducer disposed therebetween, and a resonant pipe surrounding the transducer. A gap is formed between an inner surface of the pipe and an outer surface of the transducer. Alternatively, the sound source includes a cylindrical body, a front fairing disposed forward of the cylindrical body, a plurality of metal rods connecting the front of the cylindrical body and the rear of the fairing, a spherical piezo-ceramic transducer disposed between the cylindrical body and the fairing, and a resonant pipe mounted at the front end of the cylindrical body. The spherical transducer is disposed within a cavity within the resonant pipe. A cylindrical orifice is formed between the front end of the resonant pipe and the rear of the fairing.

Some implementations provide a high-powered compact ultrasonic transducer having an integral piezoelectric ceramic force sensing element utilized to enable enhanced tissue selectivity with a piezoelectric based transducer. Some implementations additionally or alternatively relate to methods and apparatus for driving ultrasonic surgical devices, such as methods and apparatus that modulate an amplitude of a drive signal, provided to an ultrasonic surgical device, in accordance with a selected tissue selectivity level. For example, the amplitude of the drive signal for a given tissue selectivity level can be varied with time in accordance with amplitude modification parameters that are particularized to the given tissue selectivity level. Some of those implementations additionally implement a corresponding duty cycle, for the drive signal, that corresponds to the selected tissue selectivity level.

A hybrid micromachined ultrasound transducer includes a piezoelectric micromachined transducer and a capacitive micromachined transducer. The capacitive micromachined transducer is vertically stacked with the piezoelectric micromachined transducer. The piezoelectric micromachined transducer and the capacitive micromachined transducer include a common shared electrode.

An underwater acoustic transducer that is capable of radiating acoustic energy at low frequencies. A transducer which is a resonant low frequency bender-type transducer driven at its end supports by a piezoelectric stack of material operating with inner and outer parts driven in opposite directions creating a bending motion of a radiating beam, plate or disc. The small piezoelectric motions at the beam supports are magnified by the leveraged motion of the bending beam(s) creating significant output at low frequencies.

An electroacoustic transducer, comprising a piezoelectric part comprising a piezoelectric material having a first acoustical impedance and an acoustical thickness, a substrate part comprising a material having a second acoustical impedance, and an intermediate part comprising a material having a third acoustical impedance and at least partially sandwiched between the piezoelectric part and the substrate part for acoustical communication therewith. The first acoustical impedance and the second acoustical impedance each has a respective value within a range of values for which the value of third acoustical impedance: is an upper limit if said acoustical thickness is less than 0.4, or is a lower limit if said acoustical thickness is greater than 0.4 where is an acoustical wavelength in the material of the piezoelectric part.