#TechTuesday: Graphene aerogels for loudspeakers
The Graphene Flagship is making waves in the loudspeaker industry. Our partners use graphene aerogels to revolutionise a principle conceived of more than a century ago: thermoacoustics, the production of sound by rapidly heating and cooling a material rather than through mechanical vibrations.
Alexander Graham Bell patented his first electric loudspeaker, capable of reproducing intelligible speech, as part of his telephone in 1876. Over 100 years later, conventional speakers still rely on numerous mechanical parts that vibrate to create sound, housed in a speaker enclosure – in a box, essentially. This approach complicates manufacturing and limits the freedom to move or transport the speaker.
The truth is that loudspeakers could work as transducers without enclosures, but nearly all use them to improve performance. Now, the outstanding properties of graphene are enabling alternatives outside of the box.
Researchers from Graphene Flagship partners, the Italian Institute of Technology and Sapienza University of Rome, in Italy, have used ultrabroadband graphene aerogels to fabricate thermoacoustic speakers. This method leverages the excellent conductivity of graphene, enabling the conversion of audio messages into light pulses, which are then transformed into sound and recorded by a microphone that sends signals to an external amplifier.
These thermoacoustic applications of graphene offer acoustic transducers with no moving parts. Therefore, graphene-enabled speakers promise lower distortion and noise, increased bandwidth, improved transient response, and a range of other benefits over the standard industrial materials, such as paper, aluminium, and plastics.
Humans can detect sounds in a frequency range from about 20 Hz to 20 kHz, whilst a single thermoacoustic transducer based on a graphene aerogel is capable of emitting ultrabroadband sound from infrasound (1 Hz) to ultrasound (20 MHz), with no harmonic distortion.
Thanks to the lightweight and highly flexible graphene aerogel, the Graphene Flagship thermoacoustic speakers fit snugly against walls and even curved surfaces, opening up a huge range of potential rigging configurations. Graphene-enabled loudspeakers have caught the attention of designers and consumer alike, and are sure to hit the market soon. Now the future sounds clearer than ever before!