Graphene condenser mic outperforms commercial units
The researchers, based at the University of Belgrade, Serbia, created a vibrating membrane – the part of a condenser microphone that converts the sound to an electrical signal – from graphene, and were able to show up to 15 dB higher sensitivity compared to a commercial microphone at frequencies up to 11 kHz.
"We wanted to show that graphene, although a relatively new material, has potential for real-world applications" says Marko Spasenovic, an author of the paper. "Given its light weight, high mechanical strength and flexibility, graphene just begs to be used as an acoustic membrane material."
The graphene membrane, approximately 60 layers thick, was grown on a nickel foil using chemical vapour deposition, to ensure consistent quality across all the samples.
During membrane production, the nickel foil was etched away and the graphene membrane placed in the same housing as a commercial microphone for comparison. This showed a 15 dB higher sensitivity than the commercial microphone.
The researchers also simulated a 300-layer thick graphene membrane, which shows potential for performance far into the ultrasonic part of the spectrum.
"The microphone performed as well as we hoped it would" says Spasenovic. "A thicker graphene membrane theoretically could be stretched further, enabling ultrasonic performance, but sadly we’re just not quite there yet experimentally."
"At this stage there are several obstacles to making cheap graphene, so our microphone should be considered more a proof of concept. The industry is working hard to improve graphene production – eventually this should mean we have better microphones at lower cost."
For more, see the paper "Multilayer graphene condenser microphone" (PDF).
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