Multi-frequency sound production and mixing in graphene

Abstract

The ability to generate, amplify, mix and modulate sound in one simple electronic device would open up a new world in acoustics. Here we show how to build such a device. It generates sound thermoacoustically by Joule heating in graphene. A rich sonic palette is created by controlling the composition and flow of the electric current through the graphene. This includes frequency mixing (heterodyning), which results exclusively from the Joule mechanism. It also includes shaping of the sound spectrum by a dc current and modulating its amplitude with a transistor gate. We show that particular sounds are indicators of nonlinearity and can be used to quantify nonlinear contributions to the conduction. From our work, we expect to see novel uses of acoustics in metrology, sensing and signal processing. Together with the optical qualities of graphene, its acoustic capabilities should inspire the development of the first combined audio-visual nanotechnologies.

Application of three-dimensional graphene in sound generation via thermoacoustics

“…This sample was injected with a 1 kHz AC sinusoidal wave with 2 W input power and the experimental results as seen in Figure 38. The acoustic peak was received at 2 kHz, twice that of the frequency of AC input, which is in agreement with previous studies [13,93,147,[152][153][154].…”

Coupling and confinement of current in thermoacoustic phased arrays

“…3, C and D), which affords geometric control of the sound, such arrays offer opportunities that are not available in established phased array technologies. The facile, economical, and scalable fabrication methods, with potential to miniaturize down to the nanoscale and to integrate mechanical flexibility and optical transparency into the design, provide a practical route to nextgeneration audiovisual devices where a transparent electrode could double as both audio source and optical window [although, currently, the efficiency of transduction needs to be improved by several orders of magnitude for this to be practical (12)]. In particular, where flexing would cause distortion of the sound field (26)(27)(28), fine electrical control would permit simple compensation.…”

A Review on the Applications of Graphene in Mechanical Transduction

“…have shown an innovative way to modulate the sound intensity in such systems by modulating the conductivity of graphene in a GFET geometry (Figure 28K,L). [ 352 ] By controlling the gate voltage, the drain–source current is modulated by the change in conductivity, a consequence of the polarization, and an amplitude modulation is achieved. This approach facilitates the driving of a thermoacoustic generator as it removes the need for an amplifier that can withstand a constant DC current.…”