Canadian engineers, along with researchers from the European Space Agency, have developed lizard-inspired robots that could one day be crawling across the hulls of spacecrafts, doing research and repair work.
The science-fiction scenario is a step closer to reality after engineers from B.C.'s Simon Fraser University created a dry adhesive material that mimics the sticky footpads of gecko lizards.
“This approach is an example of ‘biomimicry,’ taking engineering solutions from the natural world,” said Michael Henrey of Simon Fraser.
A gecko’s feet contains millions of microscopic hairs, called setae, with ends that span just 100 to 200 nanometres across — about the size of individual bacteria. When these little hairs come into contact with a surface, it results in atomic interactions between molecules, known as the van der Waals force, which allows the lizard to stick to the surface.
Inspired by that concept, the Simon Fraser engineering team borrowed techniques from the microelectronics industry to create footpad terminators.
“Technical limitations mean these are around 100 times larger than a gecko’s hairs, but they are sufficient to support our robot’s weight,” Henrey said.
The adhesive material, which was tested in a vacuum chamber at the European Space Agency’s ESTEC technical centre in Noordwijk, the Netherlands, is able to hold up against harsh conditions in space.
“The reason we’re interested in dry adhesives is that other adhesive methods wouldn’t suit the space environment,” Henrey said.
Pressure-sensitive tapes, such as Scotch or Duct tapes, would collect dust and become less sticky over time. They would also give off fumes in the vacuum of space, which could affect delicate spacecraft systems.
Velcro is also not a viable option because broken hooks could contaminate the robot’s working environment. Magnets, meanwhile, cannot stick to composite surfaces and might create magnetic fields that would affect sensitive instruments.
“Experimental success means deployment in space might one day be possible,” said Laurent Pambaguian of the ESA.
The adhesive was placed on the footpads of six-legged crawling robots, nicknamed Abigaille. Each leg has four degrees of motion, Henrey said, meaning these crawling robots should be able to handle environments that a wheeled robot can’t.
“For example, it can transition from the vertical to horizontal, which might be useful for going around a satellite or overcoming obstacles on the way,” he said.