New Levitating, Bending 'Nanocardboard' Could Make Lightsails, Microrobots

by James Dennin

A new material developed by researchers at the University of Pennsylvania is lightweight enough to rest on a leaf without bending it, and yet may be strong enough to help propel satellites to the furthest reaches of space. Oh, and it also levitates.

And that’s not all this new material could be useful for, either. Indeed, the car hauling, cancer-cell killing, rescue operation-leading tiny robots of the future might, in fact, be made out of this futuristic cardboard.

Or, more specifically, the micro-robots of the future could be built using an aluminum-oxide “nanocardboard” that weighs less than one one thousandth of a gram and yet is strong enough to bend without breaking. It’s a great thermal insulator, meaning that it can likely hold up well in extreme temperatures.

The Penn researchers' 'nanocoardboard' perched on the leaf of an iris. 

University of Pennsylvania

The key to this fascinating new material is its sandwich-like shape, which the researchers behind it say make it about 10,000 times as strong as the material would be if it were completely solid. The team published their findings in the latest issue of Nature Communications.

“If you apply enough force, you can bend corrugated cardboard sharply, but it will snap; you’ll create a crease where it becomes permanently weakened,” says Igor Bargatin, a professor of mechanical engineering at Penn who led the study. “That’s the surprising thing about our nanocardboard; when you bend it, it recovers as if nothing happened. That has no precedent at the macroscale.”

Because it’s so strong and lightweight, the researchers said there could be a number of applications for their nanocardboard, from the small — for example by providing a material for the wings on swarming, bird-like micro-robots — to much, much larger applications in aerospace, for example by developing light sails.

The nanocardboard viewed up close under a microscope. 

University of Pennsylvania 

Light sails are one possibility for enabling humans to better explore the furthest regions of deep space without having to worry about energy constraints. They’re basically like the sails that power boats, except instead of propelling sea-bound vessels using wind, they would propel space craft or satellites by capturing the tiny light particles emitted by the sun.

“Another potential application is the Starshot lightsail, envisioned to travel at up to 20% of the speed of light in order to reach Proxima Centauri b in a couple decades,” the authors write in the paper. “Some of the critical material requirements include a mass density below 0.1 g m−2 (corresponding to a sail thickness of ~100 nm), the ability to sustain high temperatures, and a sufficient bending stiffness to control the shape (and thus the propulsion direction).”

The researchers also outlined other applications, including thermal insulation and energy conversion. The fact that the material can levitate when you heat it up, too, may also prove useful, though the researchers don’t yet seem quite certain exactly how. Next up, they plan to further investigate which of the many possible use-cases for this new nanocardboard hold the most promise.

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