The micro-robot, pictured here next to a garden snail, uses adhesive locomotion to move. (Photo provided by University of Warsaw)

Scientists in China and Poland have invented a laser-powered micro-robot that gets around by mimicking the adhesive locomotion of slugs and snails.

The 10-millimeter long robot draws its energy from a laser beam, and can move along horizontal surfaces, climb vertical walls and even make its way across glass ceilings while upside down.

Taking inspiration from the natural world is common in the field of micromechanics. Other robot-makers have designed devices that mimic the movement of caterpillars, earthworms and lizards. It is thought that one day such robots could help industrial workers perform tasks in hard-to-reach areas, like the interior of jet engines.

The snail robot, which can crawl at the speed of a few millimeters per minute, around 50 times slower than actual snails of comparable size, was developed by researchers at the Xi'an Jiaotong-Liverpool University in Suzhou and the University of Warsaw in Poland.

"Despite the slow speed, the need for constant lubrication and low-energy efficiency, our elastomer soft robot offers unique insights into micromechanics with smart materials and may also provide a convenient platform for studying adhesive locomotion," said Piotr Wasylczyk, a researcher at the University of Warsaw, who led the study whose findings were published in the journal Macromolecular Rapid Communications.

Many organisms, including earthworms and nematodes, crawl along on their bodies. But slugs and snails combine this movement with a mucus layer that allows them to move vertically and even upside down across smooth surfaces such as metal and glass.

The robot snail is made from a material called elastomer, which is comprised of liquid-crystalline particles. When stimulated by an energy source－in this case, light emitted from a laser beam－these particles can change shape and move together. The engineers also created an artificial mucus layer made of glycerin to imitate a snail trail, allowing the robot to defy gravity and cling to ceilings and walls.

The constant contact with a surface provides high margins of resistance failure, according to the researchers, giving the snail design an advantage over other microrobots that use several appendages to move.

The robot snail joins a growing number of wall-climbing machines that take their cues from the natural world. In 2010, a group of engineers at Stanford University in the United States created a robot that scales walls like a gecko.

A gecko foot has numerous tiny hairs that interact with the particles of a surface through a molecular attraction called van der Waals force.

The Stanford engineers mimicked this with a rubber-like material covered in tiny polymer hairs. The material acts as a one-way adhesive, requiring little effort to attach and detach a robot's foot, unlike designs that use suction cups.