Metallic nanofilm as resonance-free airborne ultrasound emitter

Micro liquid-based thermo-acoustic transmitter for emitting ultrasound in liquid medium

“…The experiment result proved that our device emitted a short ultrasonic pulse with the doubled frequency of the input voltage's one as discussed in the working principle. It also demonstrated the ability of our device to emit a clear short ultrasonic pulse without the unwanted tail (acoustic ringing phenomena) which is usually detected with the conventional solid ultrasound transducer [5,8].…”

“…This method were reported to have many advantages, when used in air, such as resonance-free and flat frequency response [6][7][8]. In this method, a heater is immersed directly in the medium to heat up the medium material to cause mechanical vibration.…”

Application of three-dimensional graphene in sound generation via thermoacoustics

“…The patterns of these rapid movements follow that of the temperature gradient, which was induced by the programmed AC input. This vibration couples into the surrounding medium as longitudinal waves and hence the generation of sound [13,14,19,76,77].…”

“…In this actuation method, the frequency and sound amplitude is dependent on the parameters of the input electrical signal, which will be discussed in depth in section 2.4 [77][78][79][80].…”

“…Daschewki et al investigated both the theoretical and experimental electrothermoacoustic properties of several nanometer thin sheets: titanium and indium-tinoxide (ITO) [77,80]. These materials have lower HCPUA and higher electrical resistances than gold and aluminum [13], hence making them more desirable for electrothermoacoustics.…”