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Here's how graphene mics could detect sounds beyond the range of human hearing

*Drops mic*

DAVID NIELD
4 DEC 2015
 

You've no doubt heard plenty about how graphene is going to change the world in all kinds of ways, but it's only when real, practical uses for this wonder material are discovered that its potential impact really hits home. Scientists have announced the invention of a graphene-based microphone that's dozens of times more sensitive than standard nickel-based ones, and could one day detect sounds far beyond what our ears are capable of perceiving. 

You wouldn't necessarily see these graphene mics at the next gig you go to, but they could play a significant role in exploring the Universe around us. Right now, the prototype device can only pick up audible frequencies, but the team behind the technology says it could eventually be tuned to detect faint sound waves and high frequency transmissions that would be incredibly useful to astronomers exploring the depths of space.

 

Via a chemical vapour deposition process, researchers from the University of Belgrade in Serbia were able to develop graphene sheets stretched across a layer of nickel foil. Once the nickel foil was etched away, the remaining graphene material was placed in a commercial microphone casing, converting sound to an electrical current through vibrations.

The current model offers a level of sensitivity that's 15 decibels higher than existing mics at frequencies of up to 11 kHz, but future versions could go much further if the graphene layer was made thicker.

The findings have been published in the journal 2D Materials. "Our experimental results are supported with numerical simulations," reads the report, "which also show that a 300 layer thick graphene membrane under maximum tension would offer excellent extension of the frequency range, up to 1 MHz."

"Given its light weight, high mechanical strength and flexibility, graphene just begs to be used as an acoustic membrane material," explained Marko Spasenovic, one of the paper's authors. "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."

While ultra-sensitive graphene mics probably won't be on sale at your local sound equipment store for some time, it does give us a tangible use for graphene that shows how the qualities of the new material can be used in the real world.

From solar energy to night vision goggles, there are lots of potential applications for researchers to explore, and the cost of producing the material is dropping all the time.

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