Nanotubes and Nanowires for Strong and Flexible Wiring in Wearable Devices

Carbon nanotube
Image: Pixabay

Wearable devices are gaining popularity by the day. But like any electronic device, wearables and smart clothes need strong but flexible wiring.

Physicists at Michigan Technological University studied Boron nitride nanotubes (BNNT), which could be controllable by light and pressure. In collaboration with researchers from Purdue University, Washington University and University of Texas at Dallas, the team published their findings in Nature Electronics.

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For wearable tech, electronic cloth or extremely thin devices that can be laid over the surface of cups, tables, space suits and other materials, researchers have begun to tune the atomic structures of nanomaterials. The materials they test need to bend as a person moves, but not go all noodly or snap, as well as hold up under different temperatures and still give enough juice to run the software functions users expect out of their desktops and phones, reports Allison Mills at Michigan Tech.

Yoke Khin Yap, a physics professor and the Director of Applied Physics Program at Michigan Tech, studied nanotubes and nanoparticles — discovering the quirks and promises of their quantum mechanical behaviors. He pioneered using electrically insulating nanotubes for electronics by adding gold and iron nanoparticles on the surface of BNNTs. As implied by the “tube” of their nanostructure, BNNTs are hollow in the middle. They’re highly insulating and as strong and bendy as an Olympic gymnast.

Nanotubes for wearables
The tellurium-BNNT nanowires can be as thin as 2 nanometers. (Credit: University of Texas at Dallas/Qingxiao Wang and Moon Kim)

That made them a good candidate to pair with another material with great electrical promise: tellurium. Strung into atom-thick chains, which are very thin nanowires, and threaded through the hollow center of BNNTs, tellurium atomic chains become a tiny wire with immense current-carrying capacity.

“Without this insulating jacket, we wouldn’t be able to isolate the signals from the atomic chains. Now we have the chance to review their quantum behavior,” Yap said. “The is the first time anyone has created a so-called encapsulated atomic chain where you can actually measure them. Our next challenge is to make the boron nitride nanotubes even smaller.”

The tellurium-BNNT nanowires can be as thin as 2 nanometers, while current silicon transistors on the market are between 10 to 20 nanometers wide.

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“This tellurium material is really unique. It builds a functional transistor with the potential to be the smallest in the world,” said Peide Ye, the lead researcher from Purdue University, explaining that the team was surprised to find through transmission electron microscopy at the University of Texas at Dallas that the atoms in these one-dimensional chains wiggle.  “Silicon atoms look straight, but these tellurium atoms are like a snake. This is a very original kind of structure.”