To the list of the amazing properties of carbon nanotubes has been added the ability to make nanotech loudspeakers that produce sound without mechanical movement. From nanotechweb.org, written by James Tyrrell (requires free registration): “CNT loudspeaker rips up the design book“:
A transparent carbon nanotube (CNT) thin film developed by Lin Xiao and colleagues at Tsinghua University, China, could turn out to be a wonder material for makers of audio visual devices. The see-through structure emits sound when hooked up to an electrical signal and can be stretched over a display to play audio content … eliminating the need for conventional loudspeakers or headphones.
To emit sound, the device relies on the so-called thermoacoustic effect. In other words, it is the thermal expansion and contraction of air in the vicinity of the thin film (due to the periodic heating of the CNTs) that produces sound, not the mechanical movement of the thin film itself.
…”We can batch-synthesize super-aligned CNT arrays onto 4 inch silicon wafers, which each provide enough material for a continuous thin film that can be up to 60 m long and up to 10 cm wide,” the researchers told nanotechweb.org. “Because the thin film itself does not vibrate, the loudspeaker will continue to work even if part of the film is broken or if the device is mounted on soft materials such as flags or clothing.”
The research was published in Nano Letters (abstract). The researchers also provide videos of the CNT loudspeaker working. The two links included in the nanotechweb.org article did not work for me, but the Nano Letters abstract includes the following links under “Available Supporting Information for This Article” that did work, and I found the sound to be quite respectable.
- nl802750z_si_002.qt (3.55 MB)
- nl802750z_si_003.qt (3.96 MB)
- nl802750z_si_004.qt (3.6 MB)
Microsoft Video (AVI)
- nl802750z_si_005.avi (4.29 MB)