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Giant Gecko Robots Will Save Us from Space Junk

A new gecko-inspired adhesive solves an old scaling problem for wall-climbing bots.
​One of the researchers testing the new feet. Image: ​Royal Society Interface

New designs for gecko-inspired adhesive pads that can hold more weight than previous iterations could allow bigger and more powerful robots to climb walls. Why do robots need giant gecko feet, you might ask? To catch huge pieces of space debris hurtling through the void.

Robots that can climb walls with gecko-like feet are on the come up, but they're usually pretty dinky and unsuited to the task of nabbing space junk. A smallish robot built by the European Space Agency this year, for example, used small pads of gecko-like adhesive to climb up a wall, the idea being that it could eventually do the same on the outside of a spacecraft and perform repairs while in orbit.

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According to new research, the diminutive size of past gecko-bots was mainly due to a problem of scale: gecko-inspired adhesive pads tend to lose their stickiness when the size of the pad grows beyond a couple square centimetres.

Armed with this knowledge, researchers at Stanford University designed a new kind of bio-inspired adhesive that both exceeds the scaling efficiency of a real gecko's sticky feet and could theoretically be scaled up to let a human adult climb a building. When they tried exactly that, the mega-sized gecko feet worked.

Besides humans, the researchers say, the technology could also be used to get large robots climbing like lizards.

"There have been notable efforts to scale adhesives beyond small laboratory tests, but there has been little work dealing specifically with scaling efficiency," the researchers wrote in a new paper describing their research. "Researchers have created small robots that climb well with dry adhesives, yet these systems cannot support as large a load as predicted by their total area of adhesive."

Geckoes are able to scurry around vertical surfaces thanks to the atomic interactions between millions of tiny hairs on their feet, called setae. The problem is that only a small number of setae come into contact with the climbing surface, and the gecko's weight is not evenly distributed among them. The adhesive power of a gecko is thus extremely inefficient, limiting the size and stickiness of adhesive pads, according to the researchers.

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Diagram of a climbing device utilizing the new research. Image: ​Royal Society Interface

To overcome this, the Stanford team designed a new kind of gecko-like adhesive pad that evenly distributes weight. First, hundreds of thousands of microscopic silicone wedges (an artificial facsimile of setae) were assembled into stamp-sized tiles. The tiles were then connected by specialized springs that mimicked the function of a gecko's tendons and attached to a base plate. The spring system distributed the climber's load evenly among the sticky tiles, ensuring that the pad remained sticky even if a tile fell off.

According to a report by the American Association for the Advancement of Science, the Stanford researchers are already working with NASA's Jet Propulsion Laboratory to design powerful, adhesive-equipped robots that can grasp debris like decommissioned satellites hurtling through space.

A robot equipped with the team's gecko pads has already found success in zero-g testing, where it grabbed on to the solar panel of another 881 pound robot and slowed it down.

Until now, wall-climbing robots have been rather petite, but they're about to become a lot more robust. You have to be, if you're going to be catching humongous bits of space debris while standing in the void.