Researchers at the University of Belgrade in Serbia have built the world’s first graphene-based condenser microphone, relying on graphene's ability to detect faint and high frequency sound waves. The microphone is about 32 times more sensitive than traditional nickel microphones over a range of audible frequencies. The scientists also say that in the future, graphene microphones may be able to pick up sound well beyond the range of human hearing.
The researchers used a CVD process to create 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, where it acts as a vibrating membrane, converting sound to electric current. Albeit just a prototype for now, this graphene mic boasts 15 decibels higher sensitivity than commercial microphones, at frequencies of up to 11 kHz. What's even more interesting is that 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.