15.07.15

Graphene based ultrasonic loudspeakers set to transform communications tech

AUTHOR: Inavate

Graphene has been used to build lightweight ultrasonic loudspeakers in a method that could change communication methods in the future. The project from the University of California, Berkeley will allow humans to mimic the way bats and dolphins use sound to communicate and gauge distance and speed of objects around them.

Berkley physicists say the wireless ultrasound devices can also complement standard radio transmission using electromagnetic waves in areas where radio is impractical, such as underwater, but with far greater fidelity than current ultrasound or sonar devices. They can also be used to communicate through objects, such as steel, that electromagnetic waves can’t penetrate.

“Sea mammals and bats use high-frequency sound for echolocation and communication, but humans just haven’t fully exploited that before, in my opinion, because the technology has not been there,” said UC Berkeley physicist Alex Zettl. “Until now, we have not had good wideband ultrasound transmitters or receivers. These new devices are a technology opportunity.

“There’s a lot of talk about using graphene in electronics and small nanoscale devices, but they’re all a ways away,” continued Zettl, who is a senior scientist at Lawrence Berkeley National Laboratory and a member of the Kavli Energy NanoSciences Institute, operated jointly by UC Berkeley and Berkeley Lab. “The microphone and loudspeaker are some of the closest devices to commercial viability, because we’ve worked out how to take the graphene and mount it, and it’s easy to scale up.”

Graphene membranes are also more efficient, converting more than 99% of the energy driving the device into sound, whereas today’s conventional loudspeakers and headphones convert only 8% into sound.

Zettl anticipates that in the future, communications devices like mobile phones will use not only electromagnetic waves – radio – but also acoustic or ultrasonic sound, which can be highly directional and long-range.