Leaf-shaped aquabots swim silently with 3.5x better fuel efficiency

Researchers from the University of Macau and Huazhong University of Science and Technology have developed leaf-inspired “S-aquabots” powered by programmable Marangoni motors that achieve silent, fuel-efficient movement across water surfaces. These centimeter-scale robots blend seamlessly into aquatic environments while delivering 3.5 times better fuel efficiency than conventional designs, opening new possibilities for unobtrusive environmental monitoring and aquatic robotics applications.

How it works: The S-aquabots use a programmable Marangoni motor that precisely releases ethanol through vein-like channels to create surface tension gradients for propulsion.

• Just 1.2 mL of ethanol enables navigation for 226 seconds over distances of approximately 5 meters.
• The robots can perform U-turns, rotations, and complex trajectories—including butterfly-shaped paths guided by laser spots.
• Motion remains nearly silent at ~40 dB, comparable to natural background noise.
• Their leaf-inspired shapes provide natural camouflage among floating vegetation.

In plain English: Think of how soap reduces water’s surface tension when you wash dishes—the S-aquabots work similarly by releasing small amounts of ethanol (rubbing alcohol) that changes the water’s surface properties, creating invisible “slopes” that push the robot forward without any motors or propellers.

Key capabilities: The aquabots integrate flexible hybrid electronics for multifunctional operations beyond basic movement.

• Mini-cameras enable real-time video transmission within 50 meters.
• Digital sensors support long-term environmental monitoring, recording light intensity and air temperature.
• Wireless control systems allow autonomous responsiveness and rapid communication.
• Different shapes optimize for specific functions, balancing speed, stability, and camouflage requirements.

Why this matters: These bio-inspired robots address long-standing challenges in small-scale aquatic robotics, where devices typically struggle with limited power, bulky components, and lack of precise control.

• Silent operation and natural camouflage make them ideal for ecological monitoring without disturbing wildlife.
• The Marangoni effect propulsion system eliminates the need for tethered power or bulky conventional actuators.
• Their stealth capabilities enable unobtrusive data collection in sensitive environmental settings.

Potential applications: The S-aquabots present broad utility across environmental science and emergency response scenarios.

• Water quality monitoring and pollutant tracking over extended periods.
• Search-and-rescue operations in hazardous or hard-to-reach water surfaces.
• Wildlife observation and ecological research without environmental disruption.
• Weather-related data collection in aquatic environments.

What they’re saying: “Our leaf-inspired S-aquabots demonstrate how biomimicry and advanced materials can overcome the long-standing challenges of aquatic robotics,” said corresponding author Prof. Junwen Zhong.

• “By combining programmable Marangoni propulsion with flexible electronics, we achieved both precise control and multifunctionality in untethered water robots.”
• “We believe this approach represents not only a technological breakthrough but also a blueprint for future designs of intelligent, adaptable, and eco-integrated robotic systems operating in diverse aquatic environments.”

Looking ahead: Future development could integrate sustainable energy sources like solar cells to extend operational endurance.

• The research represents a critical step toward versatile, adaptive, and eco-friendly aquatic robots.
• Applications could expand to support environmental protection, scientific research, and disaster response.
• The biomimetic approach provides a foundation for next-generation intelligent aquatic systems.