Scientists have built a tiny robotic fish that has been programmed to remove microplastics from seas and oceans by swimming around and sucking on its soft, flexible, self-healing body.
Microplastics are the billions of tiny plastic particles that scatter from the larger plastic objects in daily use – water bottles, car tires, synthetic T-shirts. It is one of the biggest environmental problems of the 21st century because once it spreads in the environment through the decomposition of larger plastics that are difficult to dispose of, and make their way into drinking water, production and food, harming the environment and human and animal health.
“It is critical to develop a robot to accurately collect and sample harmful microplastic pollutants from the aquatic environment,” said Yuyan Wang, a researcher at Sichuan University’s Polymer Research Institute and one of the study’s lead authors. Her team’s new invention is described in a research paper in the journal Nano Letters. “To our knowledge, this is the first example of such soft robotics.”
Researchers at Sichuan University have revealed an innovative solution to tracking these pollutants when it comes to water pollution: designing a small, self-propelled robotic fish that can swim around, cling to floating microplastics, and repair itself if cut. or damaged during its mission.
The robotic fish is only 13mm long and, thanks to a light laser system in its tail, it swims and rolls at about 30mm per second, similar to the speed at which plankton drifts in moving water.
The researchers created the robot from materials inspired by elements that thrive in the sea: mother-of-pearl, also known as nacre, which is the inner covering of clam shells. The team created the shell-like material by layering different microscopic layers of molecules according to the specific chemical gradient of the sweat.
This made it a robotic fish that is stretchable, flexible in twisting, and even capable of lifting weights of up to 5kg, according to the study. Importantly, e-fishes can absorb the floating parts close to the microplastics because the organic pigments, antibiotics, and heavy metals in microplastics have strong chemical bonds and electrostatic interactions with fish materials. This causes them to cling to their surface, so that the fish can collect and remove the microplastics from the water. “After the robot collects microplastics in water, researchers can analyze the composition and physiological toxicity of microplastics,” Yuyan said.
In addition, the newly created materials also appear to have regenerative abilities, said Yuyan, who specializes in developing self-healing materials. So a robot fish can heal itself at 89% of its ability and continue to suck even if it sustains some damage or cut – which can often happen if it goes looking for contaminants in rough water.
Wang points out that this is just a proof of concept, and more research is needed – particularly on how to disseminate this in the real world. For example, a soft robot currently only works on water surfaces, so Wang’s team will soon work on more functionally complex robotic fish that can go deeper underwater. However, Wang said that this electronic design could provide a launching pad for other similar projects. “I think nanotechnology shows promise in terms of tracer adsorption, collection, and detection of contaminants, improving intervention efficiencies while reducing operating costs.”
In fact, nanotechnology will be one of the most important players in the fight against microplastics, according to Philip Dimocrito, director of Rutgers University’s Center for Nanoscience and Advanced Materials Research, who was not involved in the study.
Demokritou’s lab is also focused on using nanotechnology to get rid of microplastics from the planet – but instead of cleaning them up, they’re working on replacing them. This week, in the magazine nature foodsAnnounced the invention of a new vegetable spray paint, which can serve as an eco-friendly alternative to plastic food wrap. Their case study showed that a starch-based fiber spray can fight pathogens and protect against transport damage just as well, if not better, than current plastic packaging options.
“The motto of the chemical industry for the last 40 to 50 years has been: Let’s make chemicals, let’s make stuff, put them in there and then clean up the mess 20 or 30 years later,” Dimocrito said. “This is not a sustainable model. Can we manufacture safer design materials? Can we extract materials from food waste as part of the circular economy and turn them into useful materials that we can use to address this problem?”
This is an outstanding fruit in the field of nanotechnology, Dimocrito said, and as research into materials improves, the multi-pronged approach to replacing plastics in our daily lives and filtering microplastic residues from the environment.
“But there is a big difference between invention and innovation,” Dimocrito said. “Invention is something that no one has thought of yet. Right? But innovation is something that will change people’s lives, because it makes it commercial, and it can be scaled up.”