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Microphone

Published on December 8th, 2015 | By: Stephanie Liverani

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Graphene microphone concept surpasses traditional tech with ultrasonic reach potential

Published on December 8th, 2015 | By: Stephanie Liverani

[Image above] Credit: Matthew Keefe; Flickr CC BY 2.0

 

 

The time-to-market gap for commercially viable graphene in electronic applications just keeps shrinking, with promising new developments every day that aim to manufacture graphene to produce faster, higher-performing, more efficient electronics.

 

Thanks to graphene’s single-layer thickness, toughness, and supreme mechanical and thermal properties, the material is an ideal choice for developing electronic, optoelectronic, and electromechanical devices and sensors.

 

But graphene has historically been an expensive, labor-intensive material to produce for commercial applications—and scientists continue to uncover new and innovative solutions for producing this high-potential material in a way that’s scalable.

 

This summer, we covered new research from scientists at National Cheng Kung University in Taiwan who developed a simple, cost-effective approach to produce ‘defective’ graphene in a way that they say broadens the material’s potential commercial applications.

 

And last month, we reported on research from Massachusetts Institute of Technology, where scientists are working to develop a flexible, transparent, and low-cost infrared vision system featuring graphene.

 

As the race to cost-effectively produce graphene continues, other scientists are busy putting graphene to the test in real-world applications.

 

Researchers at the University of Belgrade, Serbia, have developed a “graphene-based microphone that’s nearly 32 times more sensitive than microphones of standard nickel-based construction,” according to a recent Institute of Physics news release.

 

“We wanted to show that graphene, although a relatively new material, has potential for real world applications,” Marko Spasenovic, one of the researchers, explains in the news release. “Given its light weight, high mechanical strength, and flexibility, graphene just begs to be used as an acoustic membrane material.”

 

The team found that using graphene to create a vibrating membrane—the part of a microphone that converts sound to current—increased the microphone’s sensitivity to 15 dB. Current commercial microphones are only capable of frequencies up to 11 kHz.

 

(Check out this video below to see the inner workings of a traditional microphone.)

Credit: +AudioCheck.tv; YouTube

 

“The graphene membrane, approximately 60 layers thick, was grown on a nickel foil using chemical vapor deposition, to ensure consistent quality across all the samples,” the news release explains. “During production, the nickel foil was etched away and the graphene membrane placed in the same housing as a commercial microphone for comparison.”

 

Then the researchers upped the ante using a 300-layer thick graphene membrane to test potential ultrasonic reach.

 

“A thicker graphene membrane theoretically could be stretched further, enabling ultrasonic performance, but we’re just not quite there yet experimentally,” Spasenovic says.

 

Although the microphone performed as well as the team anticipated, Spasenovic says there are still challenges to overcome regarding graphene production—especially the costs associated with it—before their microphone can be produced at scale.

 

“At this stage there are several obstacles to making cheap graphene, so our microphone should be considered more a proof of concept” Spasenovic says. “The industry is working hard to improve graphene production—eventually this should mean we have better microphones at lower cost.”

 

The paper, published in 2D Materials, is “Multilayer graphene condenser microphone” (DOI:10.1088/2053-1583/2/4/045013).

 


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