Graphene, everybody’s favourite wonder material, has yet another trick up its sleeve. The ultra-strong, highly conductive carbon lattice is extraordinarily good at detecting faint and high frequency sound waves.
That’s according to new research from the University of Belgrade in Serbia, where materials scientists have just built the world’s first graphene-based condenser microphone. It’s roughly 32 times more sensitive than garden-variety nickel mics over a range of audible frequencies. And in the future, graphene microphones may be able to pick up sound well beyond the range of human hearing.
The researchers used a chemical vapour deposition process to “grow” sheets of graphene on a nickel foil substrate. They then etched the nickel away and placed the remaining graphene sheet (about 60 layers thick) in a commercial microphone casing. There, it acts as a vibrating membrane, converting sound to electric current.
It’s only a prototype, but so far, the team’s graphene mic boasts 15 decibels higher sensitivity than commercial microphones, at frequencies of up to 11 kHz. But model simulations indicate that a far more sensitive graphene microphone is theoretically possible. At 300 layers thick, a graphene vibrating membrane may be able to detects frequencies of up to 1MHz — approximately fifty times higher than the upper limit of human hearing.
“At this stage there are several obstacles to making cheap graphene, so our microphone should be considered more a proof of concept” said Marko Spasenovic, a co-author on the paper published this week in 2D materials “The industry is working hard to improve graphene production – eventually this should mean we have better microphones at lower cost.”
So, if you’ve got an audiophile in the family, keep an eye out for graphene mics over the next few years. They will probably be wildly expensive if and when they first hit stores. But if somebody really wants to pick up the sound of blades of grass rustling in the breeze, this seems like the way to go.
[Read the full scientific paper at 2D materials]
Top image: Atomic crystalline structure of graphene, via AlexanderAlUS / Wikimedia