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Carbon Nanotubes Enable First Step Toward Artificial Skin

Spraying carbon nanotubes onto silicone and then stretching the material creates electrodes for sensors in artificial skin

2 min read

Researchers at Stanford University have devised a method by which they can spray single-walled carbon nanotubes (SWNTs) onto a thin layer of silicone and create a flexible and stretchable pressure sensor.

The researchers, led by Zhenan Bao, associate professor of chemical engineering, published their work in the journal Nature Nanotechnology this week under the title "Skin-like pressure and strain sensors based on transparent elastic films of carbon nanotubes."

"This sensor can register pressure ranging from a firm pinch between your thumb and forefinger to twice the pressure exerted by an elephant standing on one foot," said Darren Lipomi, a postdoctoral researcher in Bao's lab, who is part of the research team, in the Stanford article covering the research.

The researchers discovered that when they sprayed SWNTs onto silicone, the SWNTs naturally formed themselves into clumps, or “nanobundles.” When the silicone was initially stretched, those “nanobundles” aligned themselves in the direction of the stretching. On release, the nanobundles form into “nanosprings,” which in the silicone material act as electrodes.

"After we have done this kind of pre-stretching to the nanotubes, they behave like springs and can be stretched again and again, without any permanent change in shape," Bao is quoted as saying in the article.

The remarkable bit is that after the initial stretching forms the SWNTs into nanosprings, they can undergo numerous stretches without losing their electrical conductivity.

The initial aim of the research was looking not for high sensitivity, but instead to exploit the characteristics of transparency and its flexibility. However, according to Bao, they need only make some changes to the surface of the electrodes to increase its sensitivity.

A video that accompanied the Stanford press release on this story (see below) provides some of the application potential for the use of the material as an artificial skin both for robotics and artificial limbs for amputees.

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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.

Avicena

If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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