3D-Printed Algae Ball Robots Promise a Practical Way to Monitor Water

Marimo, commonly known as algae balls or moss balls, is a sphere-shaped and endangered species that is endemically found around Japan and Northern Europe. They are usually situated in freshwater bottoms such as lakes and rivers and generate oxygen into the surface of the water just like other hydrophytic plants.

A research team from the University of the West of England, Bristol’s Unconventional Computing Lab has demonstrated that these green puff balls can be used to monitor some parameters such as water temperature and oxygen level. Accordingly, the team developed a device to carry out the operation and called it "marimo-activated rover system," or MARS in short.

The device is a baseball-sized and 3D-printed exoskeleton that traps the algae ball. In the simplest terms, it can be depicted as an outfit encircling the marimo as well. Neil Philips, the senior research fellow of UWE, states that the research team tested the device by fitting a marimo ball into it. During the process, the oxygen bubbles produced by marimo hit the cage and torque the sphere like a hamster ball. Thus it turns out that the transformation of photosynthesis to the fuel is succeeded. In other words, the progress can be summarized as that the exoskeleton utilizes the marimo itself for the production of its own fuel that enables it to rove across the lake floor.

Speaking of the device's mobility, there is data about the speed of MARS, too. Even though the pace of MARS depends on the level of sunlight, it can be stated that it's not a fast-moving device. As a result of the experiments, it was revealed that MARS was moving at a speed of about 3.5 inches per hour, which makes it about the same speed as a snail. Regardless of its slow speed, it nevertheless serves as a feasible and practical option for exploration and dynamic environmental monitoring.

In response to allegations that MARS will reinforce the plastic pollution in water supplies, Philips suggests that this plastic device is still more environmentally friendly than building a drone. He also adds that the device may biodegrade over time and is quite long-lasting.

The direct conversion of solar energy into physical motion has a number of benefits. According to Philips, MARS' printable, self-powered and maintenance-free design makes it a more dependable and cost-effective alternative than other systems. Now the research team aims at producing another version of the device which is compatible with saltwater environments. But this time, Neil Philips aspires to achieve this by using seaweed in place of marimo.