Researchers at the University of Leeds in the UK are using the feet of tree frogs as the inspiration for a tiny robot designed to crawl inside patients’ bodies during laparoscopic surgery. The tiny device is designed to move across the internal abdominal wall of a patient, allowing surgeons to see what they are doing on a real-time video feed.

The patterns on the tree frog’s feet provide a solution to the critical problem of getting the device to hold onto wet, slippery tissue when it is vertical or upside down. Tree frogs have hexagonal patterned channels on their feet that, when in contact with a wet surface, build capillary bridges, to create adhesion.

The frog-inspired robot has four feet—each capable of holding about 15 grams for each square centimeter in contact with a slippery surface. The researchers are aiming for a device that is 20 x 20 x 20mm, though the researchers say their prototype is almost double this size.

They are now working to halve the size of their prototype so that it can fit through the small incisions made during laparoscopic surgery. The prototype’s weight is currently of the order of 20g and can be reduced much further.