Transparent, lightweight loudspeakers could soon be incorporated into windows and computer screens after a team of Korean scientists created a working prototype.
The method relies on using a film of graphene — a one-atom-thick sheet of carbon — as the electrode material.
While graphene holds promise for a number of industries thanks to its excellent mechanical and electronic properties, one of the big challenges is to fabricate large-area films.
Jyongsik Jang and co-workers from Seoul National University used inkjet printing and vapour deposition to deposit graphene oxide onto polyvinylidene fluoride (PVDF).
The speaker system consists of a PVDF thin film sandwiched between two graphene electrodes. When an electrical current from the sound source is applied, the converse piezoelectric effect causes the PVDF film to distort, creating sound waves.
The system could also potentially be used in noise-cancelling devices by creating anti-noise waves (same amplitude but with inverted phase to the original sound).
The new system is said to have advantages over existing technology in terms of cost and power consumption. Graphene is cheaper than other electrodes, such as metals and conducting polymers, while the graphene-based acoustic actuator does not need expensive high-power voltage amplifiers owing to low power consumption.
‘The beauty of this technique lies in its potential for large-scale production and its ability to control the location of graphene — [depositing] graphene thin films on various substrates,’ said Jang.