Although I’ve mentioned my own skepticism about the utility of a flexible smartphone (see “Why Do We Want a Flexible Phone?”), the quest for that grail continues apace. Screens are just the beginning of that quest (see “Flexible Smartphone Batteries”), and researchers are now broaching the interesting question of how to achieve flexible speakers.
Flexible things are soft. But the vibrating plate of speakers can’t be soft, or they’d absorb their own sound. A seemingly insolvable conundrum.
Yet solve it Fujifilm has. The trick is to make speakers out of a material that’s hard when it needs to be hard, and soft when it needs to be soft. As ExtremeTech and others explain, the key was to develop a so-called “viscoelastic polymer.” For something to be viscoelastic, it needs to be viscous at some times, elastic at others. (Think of your Tempur-Pedic mattress, for instance, which obeys the same property.)
As a Fujifilm rep put it to Diginfo: “This film is normally soft, but it becomes hard in the audio frequency range. That’s because it’s designed so that, when the ceramic vibrates in the audio range, from 20 Hz to 20 kHz, the vibrational energy is transmitted to the entire film.” When it needs to be malleable, the film will oblige. When it needs to be rigid in order to push out those beats, the film rises to that task, too.
To prove their point in a particularly spectacular fashion, Fujifilm bent a speaker into an origami swan, and it still worked. Check out this video.
ExtremeTech has some more details on the composition of the speaker: the viscoelastic polymer is mixed with “piezoelectric” ceramic (see “A Heartbeat-Powered Pacemaker” for more on piezoelectricity), which is in turn “housed within electrodes and a protective shell.” Voltage from those electrodes causes the polymer to vibrate, producing sound. Nikkei has a few more details on how the tech works, including a strategy to release strain energy as heat, thereby preventing cracks.
It’s cool technology, for sure. Unfortunately, Fujifilm hasn’t been forthcoming about when, if ever, it stands to be commercialized. (It was touted at nano tech 2013, a conference in Tokyo that wound up last Friday.) Keep clamoring for those flexible smartphones, though, and it might just be around the corner.