Tiny robots carry up to 2,000 times their own weight
Tiny robots that can pull objects up to 2,000 times their own weight have been developed at Stanford University.
The miniature robots - dubbed MicroTugs - have power equivalent to a human dragging a blue whale, according to the website detailing the development.
The scientists behind the MicroTugs took inspiration from nature, borrowing techniques used by geckos and ants in their design.
The robots could be used in factories or on building sites.
The team at Stanford, including PhD students David Christensen and Elliot Hawkes, demonstrated a 9g robot that can carry more than 1kg vertically up glass. This is equivalent to a human climbing a skyscraper while carrying an elephant.
Another one - that weighs just 20mg but can carry 500mg, was so tiny it had to be built under a microscope, using tweezers to put the parts together.
The secret to the robots' strength lies in their sticky feet - which is copied from geckos, some of nature's most adept climbers.
"The hardest part in the development of these guys was coming to the realization that this was possible," Mr Christensen told the BBC.
He had worked on making things with the adhesive before but had not considered combining it with robotics.
"When we stepped back and thought about it, this was actually a really great use for our adhesives, with its tiny contact force required, and ability to engage and disengage many times a second," he said.
The team covered the robot's feet with tiny rubber spikes that bend and stick to a surface. When the robot picks its foot back up, the spikes straighten out again and detach.
"It was a really fun project to work on, seeing these robots in action for the first time was pretty incredible," said Mr Christensen.
The next step, he said, would be about "looking at ways to make multiples of them work together as a team, and scaling the technology up to larger bots with more industrial parts and a whole lot more force".
The Pentagon's research unit Darpa is working on a similar technique that could allow a man to scale a wall with no climbing equipment, rather like Spiderman. Its Z-Man programme was shared with the public in 2014 although it has been in development for several years.
The MicroTug robots will be on show at the International Conference on Robotics and Automation taking place in Seattle next month.