Intelligent Machines

Electronic Devices that Use Nanotubes

Prototypes bring practical nanotube devices closer.

Feb 24, 2009
Stretchy Speakers
A transparent, stretchable film of carbon nanotubes made by Shoushan Fan at Tsinghua University in China can act as a loudspeaker even when mounted on a waving flag. Overlaid on a computer monitor, the film could eliminate the need for separate speakers. Current running through the nanotubes heats the film, creating sound waves in the air through the thermoacoustic effect.
Printable Integrated Circuits
Circuits deposited with printing ­techniques are cheap to make, but the semiconducting “inks” they use tend to limit their performance. Inks using carbon nanotubes could change that. Printed nanotube circuits made by John Rogers at the University of Illinois at Urbana-Champaign are not only fast but flexible.
Conductive Clothes
By dip-coating cotton threads in carbon nanotubes, Nicholas Kotov at the University of Michigan turns them into “wires” for wearable electronics. The threads can be woven into fabrics and carry enough current to power an LED (shown here). Attaching antibodies to the nanotubes converts the fabrics into biosensors that could register pathogens or detect bleeding in patients or soldiers on the battlefield.
Transparent Electrodes
In a typical flat-panel display, liquid crystals are sandwiched between electrodes, which must be transparent so that light can pass through them. Unidym, a company in Menlo Park, CA, uses a roll-to-roll printing technique to rapidly coat plastic with carbon nanotubes. The resulting films could replace the brittle, expensive indium tin oxide electrodes used in most displays. Unidym plans to begin selling the films later this year. With Samsung, the company has made prototype e-paper readers. It’s also working on color LCDs and thin-film solar cells.