Researchers from UC Berkeley, Ajou University, and Georgia Tech unveiled Rhagobot in 2025, a tiny aquatic robot inspired by water striders of the genus Rhagovelia^[1]. The robot features self-deploying fan-like structures on its legs that harness surface tension for propulsion, mimicking the insects’ ability to move rapidly across water surfaces^[2].

The 8 cm long robot weighs just 0.2 grams and uses passive fan mechanisms that unfurl in 0.01 seconds without requiring muscle power^[3]. These fans, measuring 10 by 5 mm, enable the robot to achieve speeds of two body lengths per second and execute 90-degree turns in under half a second^[4].

According to Professor Je-Sung Koh from Ajou University, “Our robotic fans self-morph using nothing but water surface forces and flexible geometry, just like their biological counterparts. It is a form of mechanical intelligence refined by nature through millions of years of evolution”^[5].

The breakthrough came from studying the water striders’ fan architecture using electron microscopy, which revealed that surface tension alone powers the fan deployment - contrary to previous assumptions about muscle activation^[4:1]. This passive mechanism reduces power consumption compared to motorized alternatives, making it promising for environmental monitoring and search-and-rescue applications^[3:1].