Robotics is making it easier to study the effects of climate change on the environment. Using flying robots and drones can collect data in areas that are difficult to access or eco-systems which may be disturbed 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.
However, there are limitations on the use of intelligent drones at high levels for monitoring environmental conditions. These robots are made up of silicon-based electronic components, which means that they must have at least some of their parts removed in the event of a malfunction. A drone malfunction could also lead to harmful materials, such as non-degradable plastics, being dumped in fragile ecosystems. This can 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 biodegradable, bio-sourced 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.”
The drone can be launched to collect data in natural forests, and after its mission has been completed or if it fails, it can land safely on the forest’s floor. 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 is about 420mm wide and has one propeller at the rear that looks like a small glider. The wings of this flying machine are made using a combination of potato starch and cellulose ground from wood waste.
To create the wing, components are mixed together and then frozen. This turns them into an extremely stiff yet lightweight foam. 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. As the sensorized surface of the machine measures temperature, the natural world gets to work on decomposing it.
The team found that soil bacteria decomposed the majority of the drone’s wings in just 14 days. 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 components that remain in their housing. This is similar to a black box on an airplane, which must be retrieved 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.
The team has stated that in the future, the drone will have upgraded sensing capabilities. They point out that the initial temperature sensor is just a proof-of concept device and that it will be replaced by sensors which can determine the condition of soil, trees, water and other elements 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