Edible Aquatic Robots Could Be Consumed by Fish To Reduce Waste

When deploying a robot into an aquatic environment without plans to retrieve it, ensuring the device is biodegradable is crucial. Swiss scientists have advanced this idea by developing tiny robots that fish can safely eat once the robots complete their mission.

The Current State of Environmental Microbots

Various experimental micro-robots already exist, equipped with sensors and electronics, designed to roam natural environments while collecting or transmitting environmental data. Designers typically intend these devices for single use and build them with biodegradable materials. However, many still include plastics and harmful chemicals in their construction.

Aiming for a more sustainable solution, Professor Dario Floreano, PhD student Shuhang Zhang, and colleagues at EPFL (École Polytechnique Fédérale de Lausanne) developed aquatic robots that are entirely safe for the environment. Shaped like miniature boats, these robots measure about 5 cm in length, weigh approximately 1.43 grams, and can travel at speeds up to three times their body length per second.

The most surprising part?The researchers make them from fish food.

The researchers grind commercial fish feed pellets into powder, mix them with a biopolymer binder, mold the mixture into a boat shape, and then freeze-dry it to form the robot hulls.

The Internal Mechanics: Safe and Simple Chemistry

Inside each robot, there’s a chamber filled with a non-toxic mixture of citric acid and baking soda. The researchers seal the chamber at the bottom with a gel plug and connect it to a microfluidic reservoir filled with propylene glycol, which forms the top layer of the robot’s body.

Once placed on the surface of the water, moisture slowly passes through the semi-permeable gel. When water reaches the powder inside the chamber, it triggers a chemical reaction that produces carbon dioxide gas. This gas builds up in the reservoir, pushing the glycol out through an opening at the back of the robot.

The propulsion system propels the robot forward by using the Marangoni effect: the expelled glycol reduces the water’s surface tension, mimicking the movement of some aquatic insects. Importantly, the glycol is non-toxic.

So how might researchers or engineers use these robots?

Environmental Monitoring and Aquaculture

Researchers can initially deploy a group of these robots on lakes, ponds, or other bodies of water. As the robots move around randomly, their embedded sensors collect data such as temperature, pH, and pollutant levels. The system can then transmit this data wirelessly or store it for retrieval from any robots that are recovered.

Over time, the robot hulls would absorb water, soften, and begin to sink. At that point, fish or other aquatic animals could eat them. Another potential use is in aquaculture, where these robots could serve as vehicles to distribute medicated feed.

All the components of the robot will naturally biodegrade, even if no animals eat them. The next major challenge for the research team is to develop sensors and electronic parts that are also biodegradable — or even edible.

Floreano says researchers are already actively replacing electronic waste with biodegradable materials, but they have barely explored edible materials with specific nutritional profiles and functions — an area that opens up vast opportunities for improving both human and animal health.

Read the original article on: New Atlas

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