In a pioneering leap for eco-friendly technology, researchers at the École Polytechnique Fédérale de Lausanne (EPFL) have unveiled a novel aquatic robot completely crafted from edible and biodegradable materials. Mimicking the marvels of nature, this robot harnesses the Marangoni effect—a phenomenon exploited by certain water insects to glide across liquid surfaces—to achieve self-propulsion. Unlike typical robotic systems that rely on batteries and synthetic components, this ingenious design utilizes a harmless chemical reaction to generate movement, marking a transformative stride in sustainable robotics alongside environmental stewardship.
The core propulsion mechanism involves a chemical reaction housed in a tiny detachable chamber within the boat-shaped robot. When the contained reagents interact, they produce carbon dioxide gas, which then travels through a slender fuel channel. This gas expulsion lowers the water’s surface tension abruptly at the channel’s exit point, creating a gradient that thrusts the robot forward. This method operates without the need for conventional electronics or power sources, enabling silent and unobtrusive motion across various aquatic settings.
Materials-wise, the robot’s entire composition is derived from dietary ingredients safe for aquatic life and the broader ecosystem. The reaction triggers between citric acid and sodium bicarbonate—chemicals well-known from elementary science experiments involving effervescent volcanoes—while the propulsion “fuel” consists of propylene glycol, a compound widespread in cosmetics and generally recognized as safe. The resulting setup is non-toxic and biodegradable, ensuring that the device’s environmental footprint remains minimal throughout its operational life and biodegrades harmlessly after use.
This innovation emerges from a broader challenge: building functional miniature swimming robots that serve research and environmental monitoring without the ecological hazards posed by plastics, batteries, and electronic waste. “Current waterproof robots mostly rely on non-degradable components, restricting their use in fragile ecosystems," explains EPFL PhD student Shuhang Zhang. "Our work demonstrates a paradigm where these parts can be replaced with edible, biodegradable materials that offer both function and sustainability.”
The robot itself stretches roughly five centimeters in length, a size chosen to balance maneuverability and payload capacity. To construct its shell, the research team incorporated specialized fish food pellets characterized by a 30% increase in protein content and an 8% reduction in fat compared to standard commercial formulations. This decision was strategic: by integrating nutritional elements into the structure, the robot effectively doubles as a nutrient source for aquatic fauna once its functional life cycle concludes, thus closing the loop between bioengineering and nature.
Deploying such robots in swarms, the EPFL researchers envision a future where these devices function as biodegradable data collectors, equipped with sensors to measure environmental parameters such as pH levels, temperature variances, pollutant concentrations, and microbial activity in real-time. These measurements could provide invaluable insights into water quality and ecosystem health, crucial for environmental scientists and conservationists seeking minimally invasive monitoring tools.
Interestingly, precise directional control of these edible robots is limited by design choices focusing on simplicity and scalability. The team engineered two variants—‘left turning’ and ‘right turning’—by subtly adjusting the asymmetry of the fuel channel. This design ensures their trajectories mimic the erratic yet purposeful movements of aquatic insects, promoting effective environmental dispersion without the complexities of GPS-like guidance systems. Such pseudo-random locomotion allows widespread coverage of water surfaces vital for monitoring or targeted delivery of nutrients and medications.
Beyond environmental applications, the researchers speculate on using these edible robots to stimulate cognitive and behavioral growth in aquatic pets—though this hypothesis remains preliminary and requires further experimental validation. Regardless, this concept hints at a fascinating intersection of bio-robotics and animal well-being, hinting at applications that transcend traditional aquatic robotics.
This project is far from an isolated innovation; it aligns with a growing scientific movement focused on developing edible, biodegradable robotics that challenge conventional notions of machine design. The Laboratory of Intelligent Systems at EPFL, led by Dario Floreano, has spearheaded advancements including edible soft actuators that can manipulate food, fluidic circuits capable of edible computation, and conductive inks made from food ingredients for monitoring crop vitality. Each breakthrough underscores the promise of robotic systems that integrate seamlessly with biological environments and processes.
Complementing these advancements, Floreano and collaborators from the RoboFood consortium—a European Union-funded initiative worth €3.5 million—have released academic perspectives underscoring the transformative potential of robotic food. This consortium, launched in 2021, aims to explore diverse applications, from health-related nutrition delivery to environmental sustainability, rooted in the intersection of robotics and edible materials science.
At the heart of this emerging frontier lies the critical ambition to replace persistent, non-biodegradable electronic waste with materials that not only fulfill functional demands but also confer nutritional and ecological benefits. “Electronic waste remains a formidable concern globally, but edible materials with designated nutritional profiles open unprecedented opportunities for both human and animal health,” Floreano remarks, emphasizing the multifaceted impact of such research.
Beyond their environmental promise, edible aquatic robots illustrate a broader evolution in soft robotics—technologies increasingly characterized by compliance, adaptability, and bio-inspiration. By capitalizing on naturally occurring physical effects like the Marangoni propulsion, and synthesizing this with edible, non-toxic components, the EPFL team has devised robots that are as elegant as they are eco-compatible, stimulating excitement across disciplines and industries.
As these robots advance from laboratory prototypes toward real-world deployment, challenges remain in scaling production, integrating sophisticated biodegradable sensors, and optimizing operational longevity. Nevertheless, this work sets a compelling precedent for sustainable robotics, charting a course toward future technologies that live harmoniously within natural habitats while delivering critical environmental intelligence and care.
Subject of Research: Not applicable
Article Title: Edible Aquatic Robots with Marangoni Propulsion
News Publication Date: 7-May-2025
Web References:
https://www.nature.com/articles/s41467-025-59559-8
References:
Zhang, S., Floreano, D., et al. (2025). Edible Aquatic Robots with Marangoni Propulsion. Nature Communications. DOI: 10.1038/s41467-025-59559-8
Image Credits: LIS EPFL
Keywords: Soft robotics, Biodegradability, Environmental monitoring, Fish, Surface tension
