This blog consists of daily news items of interest to followers of QUIDDITY as a qualitatitive method of describing the world. This approach was described by Clive Barker in "The Great and Secret Show" and analyzed in the 149 posts of the QUIDDITY blog of this writer (see link to companion blog).
Tuesday, May 9, 2017
New: Tiny Graphene Speakers
‘Good Vibrations’ no longer Needed for
Speakers as New Research Encourages Graphene to Talk
May 4, 2017 -- A pioneering new technique that encourages
the wonder material graphene to “talk” could revolutionize the global audio and
Researchers from the University of Exeter
have devised a ground-breaking method to use graphene to generate complex and
controllable sound signals. In essence, it combines speaker, amplifier and
graphic equalizer into a chip the size of a thumbnail.
Traditional speakers mechanically vibrate to produce
sound, with a moving coil or membrane pushing the air around it back and forth.
It is a bulky technology that has hardly changed in more than a century. This
innovative new technique involves no moving parts. A layer of the atomically
thin material graphene is rapidly heated and cooled by an alternating electric
current, and transfer of this thermal variation to the air causes it to expand
and contract, thereby generating sound waves.
Though the conversion of heat into sound is not new, the Exeter team is the first
to show that this simple process allows sound frequencies to be mixed together,
amplified and equalized - all within the same millimeter-sized device. With
graphene being almost completely transparent, the ability to produce complex
sounds without physical movement could open up a new golden generation of
audio-visual technologies, including mobile phone screens that transmit both
pictures and sound.
The research is published in leading journal, Scientific
Dr David Horsell, a Senior Lecturer in the Quantum
Systems and Nanomaterials Group at Exeter and lead author of the paper
explained: “Thermoacoustics (conversion of heat into sound) has been overlooked
because it is regarded as such an inefficient process that it has no practical
applications. We looked instead at the way the sound is actually produced and
found that by controlling the electrical current through the graphene we could
not only produce sound but could change its volume and specify how each
frequency component is amplified. Such amplification and control opens up a
range of real-world applications we had not envisaged.”
The new applications the team has in mind include
ultrasound imaging, for use in hospitals and other medical facilities in the
future. The known high strength and flexibility of graphene would allow
intimate surface contact leading to much better imaging. Moreover, the fact
that the acoustic devices the Exeter
team has devised are simple and cheap make such concepts as intelligent
bandages that monitor and treat patients directly a real possibility.
Dr Horsell added: “The frequency mixing is key to new
applications. The sound generating mechanism allows us to take two or more
different sound sources and multiply them together. This leads to the efficient
generation of ultrasound (and infrasound). However, the most exciting thing is
that it does this trick of multiplication in a remarkably simple and
controllable way. This could have a real impact in the telecommunications
industry, which needs to combine signals this way but currently uses rather
complex and, therefore, costly methods to do so.”
‘Multi-frequency sound production and mixing in graphene’
by David Horsell and Mark Heath is published in Scientific Reports.