Tuesday, May 16, 2017

Scientists create a paper-thin, flexible speaker that generates energy from motion


A talking newspaper may sound like a concept from Harry Potter, but researchers say they've made a major breakthrough that could soon make it a reality.

Scientists have created a paper-thin, flexible device that can not only generate energy from human motion, but can act as a loudspeaker and microphone.

The audio device could eventually lead to a range of consumer products, including a folding loudspeaker, voice-activated security patch, or roll up radio.

The device, known as the ferroelectret nanogenerator (FENG), was created by researchers from Michigan State University.


It is made up of a silicone wafer, which is then fabricated with several layers of environmentally friendly substances including silver, polyimide and polypropylene ferroelectret.

Ions are added so that each layer in the device contains charged particles.
Electrical energy is created when the device is compressed by human motion, or mechanical energy.

Dr Nelson Sepulveda, primary investigator on the project, said: 'Every technology starts with a breakthrough and this is a breakthrough for this particular technology.

'This is the first transducer that is ultrathin, flexible, scalable and bidirectional, meaning it can convert mechanical energy to electrical energy and electrical energy to mechanical energy.'

Last year, the researchers successfully demonstrated the FENG device - by using it to power a keyboard, LED lights and an LCD touch-screen.

That process worked with a finger swipe or a light pressing motion to activate the devices - converting mechanical energy to electrical energy.

Now, they have built on that study, to extend FENG's use further.

The researchers discovered the material can act as a microphone, by capturing the vibrations from sound, or mechanical energy, and converting it to electrical energy.

It also works as a loudspeaker, by operating the opposite way: converting electrical energy to mechanical energy.

To demonstrate the microphone effect, the researchers developed a FENG security patch that uses voice recognition to access a computer, which was successful in protecting an individual's computer from outside users.


Dr Sepulveda said: 'The device is so sensitive to the vibrations that it catches the frequency components of your voice.'

To demonstrate the loudspeaker effect, the FENG fabric was embedded into a Michigan State University flag.

Music was piped from an iPad through an amplifier and into the flag, which then reproduced the sound flawlessly.

Dr Sepulveda said: 'The flag itself became the loudspeaker.

'So we could use it in the future by taking traditional speakers, which are big, bulky and use a lot of power, and replacing them with this very flexible, thin, small device.'

Imagine a day when someone could pull a lightweight loudspeaker out of their pocket, slap it against the wall and transmit their speech to a roomful of people, Dr Sepulveda said.

He added: 'Or imagine a newspaper where the sheets are microphones and loudspeakers.

'You could essentially have a voice-activated newspaper that talks back to you.'

Dr Wei Li, lead author of the study, added other potential applications of the FENG include noise-cancelling sheeting and a health-monitoring wristband that is voice-protected.

Dr Li said: 'Many people are focusing on the sight and touch aspects of flexible electronics, but we're also focusing on the speaking and listening aspects of the technology.'


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