Graphene Audio - Page 5

Chinese researchers developed and tested a highly sensitive wearable sensor, made of woven thin films of graphene on elastic polymer/double sided tape film, for sound signal acquisition and recognition.

(a) Key steps of preparing the graphene strain sensor; (b) Three ways of collecting and recognizing human voices; (c) Photograph of a bent strain sensor; (d) SEM image of GWFs; (e) Signals of vocalization (black) and un-vocalization (red) are nearly overl

When the sensor is stretched, random cracks appear and decrease the current pathway (increasing the resistance). The film could therefore act as a strain sensor and can be, for instance, put on human throats to measure a person's words through detection of muscle movement, even without actual words being sounded.

Researchers from the University of California, Berkeley, have developed a new graphene-based earphone-sized speaker - that can actually outperform the best earphones. They say that even with almost no specialized acoustic design, it performs comparably to a high quality commercial headsets (a Sennheiser MX-400 earphone, in fact)

This speaker uses a diaphragm that is made from a multi-layer graphene sheet. The graphene is sandwiched between two electrodes that create a field that oscillates, causing the graphene to vibrate. The performance is so good because graphene is inherently very thin and strong, and it can be configured to have very small effective spring constant - it's the perfect diaphragm material.

Researchers from Seoul's National University developed a transparent and lightweight speaker made from Graphene. This may enable speakers embedded in windows or displays. It may be especially suited to develop noise-cancelling devices.

The graphene speaker was made by depositing graphene-oxide onto poly vinylidene fluoride (or PVDF) and then reducing it to create a graphene film (this is actually a new method to develop graphene films). So basically this speaker is made from PVDF sandwiched between two graphene electrodes. When an electrical current (from the sound source) is applied, the converse piezoelectric effect causes the PDVF film to distort - and thus sound waves are created.