Paris: Inspired by the gecko, scientists have developed a tank-like robot that can scale vertical walls and crawl over ledges without using suction cups, glue or other liquid bonds to adhere to the surface.
The 240-gramme beast has tracks that are covered with dry microfibers modelled on the toe hairs of the gecko, which can famously zip up windows and along walls almost without effort.
Lizard does the trick thanks to millions of ultra-fine hairs called setae, which interact with the climbing surface to create a molecular attraction known as the van der Waals.
today in the British research journal Smart Materials and Structure, the robot's tracks are studded with mushroom-shaped caps of polymer microfibers just 0.017 millimeters wide and 0.01mm high.
By comparison, the human hair is around 0.1 mm thick.
"While van der Waals forces are considered to be relatively weak, the thin, flexible overhang provided by the cap ensures that the area of contact between the robot and the surface is maximised," said researcher Jeff Krahn of the Simon Fraser University at Burnaby, in Canada's British Columbia province.
"The adhesive pads on geckos follow this same principle by utilising a large number of fibres, each with a very small tip. The more fibres a gecko has in contact, the greater attachment force it has on a surface."
The tank-bot has a fore and aft section, each with two tracks, and an articulated joint in the middle to help it move from flat surfaces to corners.
A video ( shows it being put through its paces, climbing at speeds of up to 3.4 centimeters per second.
The gadget weighs 240g but tests show that it could take an additional load of 110 grammas.
Still a small experimental design, the robot is attached to an umbilical cord providing power and control signals, but eventually will be kitted out with a battery and a computer brain to give it more autonomy, says the team.
If all goes well, dozens of applications lie ahead.

Wall-climbing robots could be used to clean windows, inspect buildings, crawl up pipes and help in search-and-rescue operations.