Nature often outsmarts and outpaces our ability to design various systems with specific and necessary roles in the ecosystem. We have much to learn from these systems, and constructing artificial structures that mimic their beneficial aspects is advantageous for numerous applications. So, it makes sense that devices created to carry out biologically related functions based on natural processes are referred to as “bio-inspired.”
Although nature uses many processes to “clean” water – improving water quality and reducing water pollution are important challenges worldwide – technological advancements such as 3D printing provide scientists with new tools for tackling these problems. Researchers at the University of Bristol in the UK, led by Drs. Rossiter and Ieropoulos, set out to develop a robot resembling an organism known as the water boatman beetle, an aquatic insect with oar-like legs.
Robotics applications are typically limited by how long a robot can function before running out of energy. Inspired by Wilkinson’s famous Gastrobot developed in the late 1990s, which contained a microbial fuel cell that could break down food into molecules that are then used to produce energy, the researchers in Bristol incorporated structures inside of a 3D printed chamber to make their Row-bot autonomous. Additionally, the researchers wanted this device to float on water. However, the Gastrobot (and related Eco-Bot) are huge, making them quite unsuitable for floating. Thus, they also had to miniaturize the devices to ensure that they wouldn’t sink. An opening similar to the beak-like mouth of the water boatman beetle was incorporated into the structure and the “legs” were prepared by 3D printing.
By integrating structures that could take advantage of compounds present in pond water for producing electrical energy, the scientists had created their Row-bot. The microbial fuel cell “stomach” ingests bacteria or other organic matter present in the water and converts these substances into electricity. This energy can be used to propel the Row-bot to another location, where it can ingest more organic matter and produce more energy.
So, what is all of this effort good for? By building these systems in part by using simple 3D printing procedures, large numbers of Row-bots have the potential to digest contaminants in water such as algal blooms, oil spills, and bacterial contamination.
Of course, there are many questions still open to researchers: how will these little robots be removed from the water once the pollution is alleviated? Could a magnet be included for easy collection? How might they be useful in larger bodies of water, such as oceans? Can these structures be produced on a larger scale, more like the size of a shark? If they cannot be removed from the water, is it possible to make them biodegradable?
Other 3D printing efforts have been undertaken to develop robots for sensing pollution, bringing important information to scientists who can remain on shore. A research team in France invented the “Envirobot,” an eel-shaped robot that can swim around and detect pollution. The shape of this robot prevents it from becoming entrapped in debris in the water. The Envirobot can swim in a predetermined pattern or create its own path through the water. This 3D printed robot can detect things such as changes in conductivity (indicating the salt concentration in the water) and temperature, as well as the presence of various compounds.
Even larger, a collaboration between researchers in China and Alabama resulted in the production of a biocarrier for use in a biofilm reactor. A biofilm reactor removes organic matter, phosphorous, and nitrogen-containing components from water for recycling. To achieve this goal, a biocarrier is needed, which is a piece of plastic that collects various biological components in a water purification device. By 3D printing these biocarriers, the specific properties can be precisely controlled. 3D printed biocarriers show improved properties such as higher bioactivity over traditionally prepared carriers at a lower cost, and thus can be used to improve the efficiency of wastewater treatment.
From robots that you can hold in your hands to wastewater treatment plant components, 3D printing is expanding the repertoire of available methods for providing clean water and reducing pollution. The development of these devices is only the first step. Motile robotic machines may even be useful in the human body for transporting drugs or molecules necessary for tissue repair. As more miniaturized structures are developed and the ability to fine-tune their properties becomes more advanced, the biological application potential of 3D printed “swimming” machines, or Row-bots, will be exciting to watch.