Scientists Develop Floating Robot Inspired by Water Strider

Nature’s mysteries never cease to amaze. Around lakes or ponds, one can often spot floating insects like water striders gliding effortlessly amidst water hyacinths and other aquatic plants. These tiny creatures not only float on water but also maintain balance during large waves. Now, a team of scientists from the University of California, Berkeley, the Georgia Institute of Technology, and Ajou University in South Korea has created a robot inspired by these aquatic insects. The robot, modeled after the Rhagovelia water strider, also known as the ripple bug, can move seamlessly across the water’s surface, replicating the insect’s unique locomotion technique.

The Rhagovelia water strider has fan-like structures on its legs that open and close at will, without relying on muscle power. Research shows these insects can close their fans in just one-fiftieth of a second—ten times faster than the blink of an eye. This rapid movement allows them to change direction swiftly and cover distances up to 120 times their body length per second.

Scientist Victor Ortega-Jiménez remarked, “When I first saw these insects, I was fascinated. They were darting around so quickly, they seemed like flying insects. We wondered how such tiny creatures could move like that. It took over five years to find the answer. For years, scientists believed these fan-like structures relied on muscle power. Our recent study revealed that the water’s surface tension and elasticity work in perfect harmony to drive their movement. The fan opens almost instantly upon contact with water, enabling rapid movement and turns in under a second.”

South Korean scientist Je-Sung Koh and his team unraveled this mystery by capturing microscopic images of the fan-like structures. The images revealed that the fans are not cylindrical like hair but flat and ribbon-like, providing rigidity for propulsion when needed. Based on this discovery, the team developed a one-milligram micro-robot called the Rhagobot, which uses water’s surface tension to self-deploy its fans, mimicking the insect’s agility, braking, and maneuverability. Professor Je-Sung Koh stated, “Our robot, like its biological counterpart, uses water surface tension and flexible geometry to propel itself.” This breakthrough, published in *Science*, offers potential applications in environmental monitoring and search-and-rescue missions in turbulent waters