Scientists at the École Polytechnique Fédérale de Lausanne (EPFL) have developed a unique robot. This small, boat-shaped aquatic device is edible and biodegradable, offering a safe and eco-friendly alternative to traditional monitoring tools that use electronics and plastic. It opens up exciting possibilities for product designers, landscape architects, packaging designers, and biodesigners who seek sustainable and circular material solutions.

How Does It Work?

The edible aquatic robots move by copying a natural effect found in insects, called the Marangoni effect. This effect helps small creatures skate across water surfaces. Inside the robot, a simple chemical reaction between citric acid and baking soda produces carbon dioxide gas. This gas pushes liquid fuel (propylene glycol) into the water, which lowers the water’s surface tension. The change in surface tension makes the robot glide across the water.

This method is safe for animals and harmless to the environment. The materials are common, including propylene glycol, which you often find in skincare products.

Unlike many other robots that use plastics, batteries, or electronics, this device is completely biodegradable. At the end of its life, the robot won’t add waste to the environment.

A Robot That Feeds Fish

The outer shell of the robot is made from fish food. This material is high in protein and low in fat, making it safe and even beneficial for aquatic animals. When the robot stops working, it becomes a source of food. This design shows how materials can support both functionality and the health of ecosystems. For designers, this is a strong example of creating materials that are bio-based, biodegradable, and beneficial.

Potential Uses

The EPFL team hopes to use these robots in large numbers for environmental monitoring. Each robot can carry sensors that collect data such as water pH, temperature, pollution levels, and microorganisms. These edible aquatic robots could also deliver nutrients or medicine to fish in controlled environments, like fish farms.

The robot’s movement is random, but the design allows for some control. By changing the shape of the fuel channel, the team created versions that tend to turn left or right. This simple system helps scatter the robots across the water, similar to how insects move.

A New Field of Edible Robotics

This project is part of a growing field called edible robotics. The team at EPFL has also worked on edible actuators for soft robots, edible fluidic circuits for simple computers, and edible ink for monitoring plants. The RoboFood project, funded by the EU, supports their research.

By combining biodegradability with nutritional value, these robots show how materials can be both functional and safe for nature. For designers interested in circular materials, this is a valuable step forward.

Source: EPFL
Photo: Alain Herzog