A biodegradable drone for environmental monitoring
The boom in robotics makes it possible to do this research more efficiently and less labor-intensively. Using flying robots and drones can collect data in areas that are difficult to access or eco-systems which may be disturbed easily by scientists. in situ investigations.
These include natural forests, which are one of the world’s largest carbon sinks, and thus important in reducing carbon dioxide, a major greenhouse gas and driver of climate change.
Although there are some limitations, the use high-level intelligence drones in environmental monitoring is still possible. These robots are made up of silicon-based electronic components, which means that they must have at least certain parts. This requires the collection of drone sections in case of a failure or loss of control. A drone failure can also lead to harmful materials, such as non-degradable plastics and metals, being dumped in fragile ecosystems. This could threaten a delicate equilibrium.
A biodegradable flying machine
The journal has published a new article Advanced Intelligent Systems This project proposes an improvised flying robot made of mostly biodegradable, biosourced and renewable materials.
“In this specific example, the structure, as well as the printed environmental sensors, are fully degradable. Most of the drone’s components can be left in the environment targeted for monitoring, and one-way missions are enabled,” said Fabian Wiesemüller from the Laboratory of Sustainability Robotics, Empa — Swiss Federal Laboratories for Materials Science and Technology, who led the study with colleague Mirko Kovac. “Furthermore, the bio-based materials used generally have a smaller environmental footprint and make the device more sustainable.”
In the case of malfunction or when the mission has been completed, the flying drone could be dropped on the forest’s floor to decay. This is because the “ingredients” of the drone are simple starch, agar, and gelatin mixed with some wood waste.
Wiesemüller and Kovac’s team from the Sustainability Robotics Lab intend to use the data from the smart drones to monitor the condition of forests and their biological and chemical balance.
A palm-sized glider
The drone’s wingspan is approximately 420 mm. It has no tail and resembles an palm-sized glider. This flying machine’s wings, which are composed of potato starch and agar combined with wood-waste cellulose ground to a fine powder, is incredibly exciting.
Mixing the components and freezing them turns into an extremely stiff, lightweight foam which can then be formed into a wing-shaped shape. To reinforce the wing, an ultra-low roughness electronics paper was bonded to the wing’s core.
“While cellulose is the most abundant polymer on Earth, its mechanical properties and inherent sustainability make it an ideal candidate for the design of transient robots,” Wiesemüller said. “By mixing it with the other three biopolymers, lightweight bio-based and fully biodegradable high-porosity foams were developed.
“After the mechanical analysis of various compositions, it was found that cellulose and gelatin feature the best properties, maximizing the specific stiffness and specific strength,” he continued.
To this structure, the team attached a sensorized skin made from carbon black sensors ink jet printed on cellulose according to Wiesemüller, with this component also being biodegradable.
“A commercial desktop ink-jet printer was used with a carbon-black based ink. The ink was deposited on low-roughness electronics paper and the samples were dried using a heated pad,” the scientists continued. “The resulting printed sensors are low-cost, and their design can be changed quickly due to the flexible manufacturing approach.”
Thus far, only one section of the drone doesn’t decay to the forest floor, but the scientists have ensured this element will do as little environmental harm as possible.
“The fuselage section carries an electronics box, which holds the non-degradable components, such as the data link and flight controller, and acts as a crash box reducing the risk of contaminating the environment,” Wiesemüller pointed out.
How does the decaying drone perform?
The team behind the drone said that once it lands on the forest floor at the end of service life, a “race against time” begins. While the skin on the machine senses the temperature, the natural world gets to work.
After only 14-days, soil microorganisms had broken down most of the drone’s wings. After two weeks, the sensing skin started to break down. The decomposition allowed the drone’s components to return to nature. It is only the electronic parts that remain in the black boxes used on airliners, which will need to be collected at a future date.
The team’s drone has already made several test flights during which it was manually piloted and demonstrated its flight stability, achieving continuous data streaming of the incorporated sensors. Wiesemüller added that the flying wing had high agility and could sustain flight for as long as 15 minutes.
In the future, the drone will have improved sensing abilities. The team points out that, while the current temperature sensor is a proof-of concept device, it will soon be replaced by sensors which can determine in real time the conditions of trees, soil, and water across the landing zone.
“In the next step, we want to incorporate other transient sensors, that can provide more information on the environment. This includes indicators such as relative humidity, UV intensity as well as pollutant levels,” Wiesemüller concluded. “Furthermore, we are working towards substituting more and more non-degradable components such as the battery with transient electronic components.”
References: F. Wiesemüller, et al, Biopolymer Cryogels for Transient Ecology-Drones, Advanced Intelligent Systems, DOI: 10.1002/aisy.202300037
Feature image credit: Yusuf Furkan Kaya