Mister Fantastic might not be the hottest superhero in the extensive Marvel Universe roster right now. But there's no denying the Fantastic Four leader's power to stretch and contort his plasticky limbs into any nook or cranny has helped save the day (and the world) many times over.
While Reed Richards is alas only fictional, a new snake-like robot developed by researchers in the US exists beyond the realm of comic books – and its ability to twist and grow in any direction like a possessed, sentient vine could one day be able to save endangered lives for real.
Inspired by organisms that cover distance by growing – such as vines and nerve cells – the team's tentacular prototype may look creepy as all hell while it slithers and probes, but it represents a new kind of soft robotics that can move in ways that no known conscious being can.
"Essentially, we're trying to understand the fundamentals of this new approach to getting mobility or movement out of a mechanism," says mechanical engineer Allison Okamura from Stanford University.
"It's very, very different from the way that animals or people get around the world."
The robot works on the principle of eversion – like a rolled up, inside-out sock, the robot's soft body is folded within itself.
So, to extend in any direction, it unfurls its plastic innards, regurgitating its body forward, meaning its ever-changing front tip consists of the most recently surfaced new skin. (Watch the video below, it sounds a lot grosser than it is.)
"The body lengthens as the material extends from the end but the rest of the body doesn't move," says one of the team, Elliot Hawkes from the University of California, Santa Barbara.
"The body can be stuck to the environment or jammed between rocks, but that doesn't stop the robot because the tip can continue to progress as new material is added to the end."
Of course, for the process to work well enough for you to actually get anywhere worth going, you'd need to be a pretty long (swallowed) sock. Fortunately, the team's prototype measures an amazing 72 metres (236 ft) in length when fully extended, meaning the robot can ultimately transport itself over a pretty sizeable distance.
Even more impressive though is its pace – with a top speed of 35 kilometres per hour (21.7 mph), this thing can unfurl like nobody's business, although the researchers' primary interest is its ability to navigate through tricky, twisting surroundings like mazes, aided by a camera and algorithms that help it decide which paths to take.
"The applications we're focussing on are those where the robot moves through a difficult environment, where the features are unpredictable and there are unknown spaces," says one of the researchers, Laura Blumenschein.
"If you can put a robot in these environments and it's unaffected by the obstacles while it's moving, you don't need to worry about it getting damaged or stuck as it explores."
The current prototype is filled with air and is powered by pneumatic air pressure that pushes the plastic skin out.
The researchers think future versions could be made with tougher material like kevlar, which could enable the robot to be filled with other material such as water, helping save the lives of people trapped under rubble in emergency situations.
Already the prototype could hypothetically be used to help find victims in such scenarios, with the robot's vision potentially being broadcast back to human rescuers, who could then set about freeing those trapped.
Even there the robot might be able to help – its ability to inflate can actually be used to lift heavy objects (up to 100 kilograms or 220 lbs) by sliding underneath them before expanding its body.
In testing, the prototype successfully navigated itself through a number of contrived obstacle courses, besting flypaper and ice walls, and even survived being punctured by nails protruding from a wall.
It also does stealth with aplomb: it can sneak under a thin door gap and then expand itself on the other side, or travel through vanishingly thin crevices in order to deploy survival tools, such as a radio communicator.
"Much like vines can transport nutrients along their length, you can imagine that a grown robot body could be used to deliver supplies and payloads or form a communication path," Blumenschein explained to Jordan Pearson at Motherboard.
"Or, with different material choices, you could use the grown body as a structure itself, to provide supporting forces to the environment."
Sounds pretty fantastic to us.
The findings are reported in Science Robotics.