Scientists at Seoul National University (SNU) (www.en.snu.ac.kr) in Korea and Harvard University (www.harvard.edu) in the USA have worked together to create a ‘leggy’ micro-robot that mimics the actions of ‘water striders’.

To understand how these insects jump without sinking, researchers filmed one with high-speed cameras.

They saw that its legs are swept inwards and accelerate gradually but do not lose contact with the water until it is time to jump. The force used does not exceed the water’s surface tension; it is precisely the right amount of force to jump without sinking.

Kyu Jin Cho, associate professor in the Department of Mechanical and Aerospace Engineering at SNU, said: “The water’s surface needs to be pressed at the right speed for an adequate amount of time in order to achieve jumping. The water strider is capable of doing all these things flawlessly.”

The scientists determined that the smoothest way to jump off water involves maintaining leg contact on the fluid surface for as long as possible during the period of ‘locomotion’.

The robotic insect can exert up to 16-times its own body weight on the water’s surface without breaking through.

Donald Ingber, of Harvard’s Institute for Biologically Inspired Engineering, said: “This international collaboration of biologists and roboticists has not only looked into nature to develop a semi–aquatic bio-inspired robot that performs a new extreme form of robotic locomotion; it has also given us new insights into the natural mechanics at play in water striders.”