Nature has always been a treasure trove of inspiration for human technological innovation. Drawing inspiration from aquatic insects like water striders, a research team at the University of Virginia’s School of Engineering and Applied Science has successfully developed two robotic prototypes that can float and move on the surface. The research results were published in Science Advances, a journal under Science. They not only demonstrated the cutting-edge progress in robotics technology, but also opened up a new path in materials science and flexible device manufacturing.
The two robots, named “HydroFlexor” and “HydroBuckler,” each have distinct characteristics, emulating the locomotion mechanisms of different aquatic organisms. The HydroFlexor propels itself by mimicking the fin-like movement of fish, offering smooth, continuous motion suitable for surface tasks requiring stable propulsion. The HydroBuckler, on the other hand, mimics the paddling motion of water striders, “walking” across the water with a unique curved gait, demonstrating excellent maneuverability and surface adaptability. Both designs embody the core principle of biomimetic robotics: “learning from nature,” translating the locomotional intelligence of living things into engineering reality.
However, the key to these robots’ ability to “float” lies in the ultra-thin, flexible, specialized films they employ. Traditionally, such films must be fabricated on a rigid substrate like glass and then transferred to a water surface. This process is not only cumbersome but also prone to film breakage due to uneven stress or improper handling, limiting its practical application. The Virginia team has innovatively developed a novel method for fabricating films directly on a liquid surface: they drop liquid polymer ink onto the water surface, leveraging its natural diffusion to form an ultra-thin, seamless film. High-precision laser cutting is then used to create the contours of the robot’s limbs and torso directly on the surface. This method not only effectively eliminates the risk of breakage during transfer but also enables an integrated manufacturing process from film preparation to structural formation.
These specialized films utilize a two-layer composite structure. Their core driving mechanism lies in the thermal response of the material: when exposed to external infrared light, the differential thermal expansion rates of the two layers cause the film to undergo controlled bending deformation, directly converting thermal energy into mechanical driving force. This photothermal actuation method eliminates the need for an internal power source or complex transmission mechanisms, significantly simplifying the robot’s structure and improving the system’s reliability and environmental adaptability.
The breakthrough of this technology lies not only in resolving the transfer challenges associated with flexible material manufacturing but also in providing a new paradigm for directly constructing functional flexible devices in liquid environments. The research team emphasizes the broad applicability and scalability of this latest breakthrough: it is compatible with a variety of functional ink and liquid substrate combinations and has the potential for large-scale production. This means that in the future, it will not only enable the customized manufacturing of various aquatic robots, but also expand into other fields requiring ultra-thin flexible devices.
In practical applications, aquatic robots based on this thin-film technology show broad potential. They can be deployed for water quality monitoring, floating on lakes, rivers, or offshore for extended periods to collect real-time water quality parameters. In disaster relief, such robots can easily navigate flooded areas for search and rescue or environmental monitoring. Furthermore, they can be integrated with various environmental sensors to form distributed sensor networks for ecological research or pollution tracking.
Notably, the potential applications of this technology extend far beyond the aquatic robotics sector. The resulting ultra-thin, elastic, and shapeable film manufacturing process provides a critical material foundation for the development of wearable medical devices, such as skin-fitting health monitoring patches and drug delivery systems. This technology also opens up new avenues for the fabrication of next-generation flexible electronic components, potentially enabling the development of cutting-edge products such as highly durable flexible displays, foldable circuits, and even electronic skin.
Overall, this University of Virginia research, through interdisciplinary innovation, successfully transforms fragile thin film materials into robust and practical robotic platforms and functional devices, achieving the efficient transition from natural inspiration to technological achievement. This not only advances the development of aquatic robotics but also sows the seeds for far-reaching impact in fields such as flexible electronics, biomedicine, and environmental sensing. With further research and process optimization, this disruptive concept of “building robots directly on water” may become a key paradigm for future flexible system manufacturing, continuously pushing the boundaries of human capabilities in areas such as water management, emergency response, and intelligent perception.
