A microphone made from a single layer of atoms could shrink the one in your smartphone by more than 200 times, allowing for better noise cancellation without bulking up your device.
Most modern microphones consist of a membrane that vibrates when hit by sound, in turn converting that vibration into an electrical signal. at Delft University of Technology in the Netherlands and his colleagues have developed one that instead works using lasers.
Their membrane is made from a tiny sheet of graphene 鈥� a single layer of carbon atoms 鈥� stretched over a silicon cylinder filled with air. The team sets the membrane vibrating at its resonant frequency by hitting it with a laser. When a sound enters the microphone, the air pressure inside changes and this, in turn, alters the resonant frequency. By measuring this change with another laser, the team can reconstruct the original sound.
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To test the microphone, the researchers recorded the theme song from the video game Super Mario Bros. and found that it could record a similar range of frequencies to a conventional microphone, though the recording is less clear.
The main advantage of their graphene system is that it can be much smaller than a conventional microphone, says Verbiest, and would need a membrane that is just 10 micrometres across 鈥� an area 200 times smaller than a similarly performing conventional microphone.
鈥淔or the same area that you have in your phone, you can put multiple microphones, which means that you can really identify the direction of sound,鈥� says Verbiest. This could help with noise cancellation and audio recording.
One issue is that the laser system needed to read an audio signal from the membrane is much larger than the graphene sheet itself, says at the University of Nottingham, UK, and this would also have to be miniaturised. 鈥淚t is original and it鈥檚 an interesting idea, but it needs a fair amount of development before you鈥檇 see it in a mobile phone,鈥� he says.
arxiv
