A snail-inspired robot may one day scoop up microplastics from the surfaces of oceans, seas and lakes.

Scientists from Cornell University in the state of New York, US, based the prototype design on the Hawaiian apple snail, a common aquarium snail that uses the undulating motion of its foot to drive water surface flow and suck in floating food particles.

Sunghwan Jung, professor in the department of biological and environmental engineering, said, “We were inspired by how this snail collects food particles at the water and air interface, to engineer a device that could possibly collect microplastics in the ocean or at a water body’s surface.”

Currently, plastic collection devices mostly rely on drag nets or conveyor belts to gather and remove larger plastic debris from water, but they lack the fine scale required for retrieving microplastics.

These tiny particles of plastic can be ingested and end up in the tissues of marine animals, entering the food chain where they become a health issue and potentially carcinogenic to humans. Plastic waste makes up 80% of all marine pollution, with 8 to 10 million metric tons of plastic ending up in the ocean each year, according to the UN Economic and Social Council.

The prototype robot, modified from an existing design, would need to be scaled up to be practical in a real-world setting. Researchers used a 3D printer to make a flexible carpet-like sheet capable of undulating. A helical structure on the underside of the sheet rotates like a corkscrew to cause the carpet to undulate and create a travelling wave on the water.

Analysing the motion of the fluid was key to this research.

“We needed to understand the fluid flow to characterise the pumping behaviour,” Jung said. "The fluid-pumping system based on the snail’s technique is open to the air."

The researchers calculated that a similar closed system, where the pump is enclosed and uses a tube to suck in water and particles, would require high energy inputs to operate.

The snail-like open system is far more efficient - the prototype, though small, runs on only five volts of electricity while still effectively sucking in water, said Jung, who is senior author of the study, published in Nature Communications journal.

The study was funded by the National Science Foundation.