Representational image. Getty Images
Tiny robots inspired by insects could soon glide across water, scouting flooded areas, monitoring pollutants, or collecting samples, thanks to a breakthrough in soft robotics.
Researchers at the University of Virginia’s School of Engineering and Applied Science have created two prototype devices that demonstrate what’s possible.
The first, HydroFlexor, paddles across water with fin-like motions. The second, HydroBuckler, “walks” forward using buckling legs, mimicking the gait of water striders.
Powered in the lab by an overhead infrared heater, these robots bend and move as their layered films respond to heat.
Cycling the heat on and off allows the robots to adjust speed and even change direction — proof that controlled, repeatable motion is possible at this tiny scale.
The key to making these insect-inspired machines is a novel fabrication method called HydroSpread, introduced by Baoxing Xu, professor of mechanical and aerospace engineering.
Unlike traditional approaches, HydroSpread lets ultrathin polymer films form directly on water, eliminating the fragile and error-prone step of transferring films from rigid surfaces.
“Fabricating the film directly on liquid gives us an unprecedented level of integration and precision,” Xu said.
“Instead of building on a rigid surface and then transferring the device, we let the liquid do the work to provide a perfectly smooth platform, reducing failure at every step.”
Droplets of liquid polymer naturally spread into uniform sheets on the water’s surface, which can then be carved with a laser into complex patterns, from circles and strips to the UVA logo, with remarkable precision.
HydroSpread’s approach allows scientists to produce delicate, floating devices that would have been difficult or impossible to make using conventional methods.
By removing the fragile transfer stage, the method improves yield and enables more ambitious designs in soft robotics.
The implications stretch further than soft robotics. HydroSpread could make it easier to produce delicate films for wearable medical sensors, flexible electronics, and environmental monitors. Such devices must be thin and resilient, capable of working where rigid materials fail.
By sidestepping the fragile transfer process and enabling direct fabrication on liquid, Xu’s method could transform how scientists design lightweight, adaptable technologies across multiple fields.
“Instead of building on a rigid surface and then transferring the device, we let the liquid do the work,” Xu emphasized.
For now, HydroFlexor and HydroBuckler are only lab-scale prototypes. But their insect-like movements hint at a future where fleets of miniature robots could glide across water, performing tasks once too dangerous or delicate for humans.
The findings of the study have been published in Science Advances.
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