How this drone collects DNA samples from tree branches without breaking them

Monitoring and cataloging the environmental DNA left behind by animals and insects is not an easy task. Insect DNA is usually detected using traps; which leads to her being killed.

Although specimens of these insects and animals are easy to obtain from water or soil, accessing them in forests and other unexplored areas is challenging.

For these reasons, researchers at ATH University of Technology in Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research - known as "WSL" - and the company "Spygun" were involved. are in partnership to develop a unique drone that can independently collect samples from tree branches, according to the Science Robotics website .

Landing on the branches

The mechanism may seem simple, but in fact it uses very complex technology. The drone is equipped with adhesive strips, so that the material from the tree sticks to these strips when the drone lands on the branch.

Researchers can then extract the environmental DNA in the lab and catalog it using database comparisons.

"Landing on branches requires complex control," Stefano Minchev, professor of environmental robotics at ATH University of Technology, said in a statement. The branches vary in thickness and flexibility, and can bend and bounce when a drone lands on them; Therefore, the aircraft is programmed to approach the branch on its own, and to remain stationary on it to take samples; This was a great challenge for scientists.

Since the drone cannot understand the elasticity of the branch, the researchers equipped it with a force-sensing cage that enables the drone to measure at the scene.

The aircraft was tested on 7 species of trees, and the samples revealed DNA from 21 distinct groups of organisms, or taxa, including birds, mammals and insects.

"This is encouraging because it shows that the sampling technique is working," Mintchev said.

Preparing for a trip in the rainforest

Mintchev and his team are currently preparing the drone for a competition in Singapore, where the drone has to detect as many different species as possible across 100 hectares of rainforest in 24 hours.

The team is working in the Masola rainforest at Zurich Zoo. "Here we have the advantage of knowing which species are present, which will help us better assess how thoroughly we have captured all traces of environmental DNA using this technique or if we have missed something," Mintchev said.

Collecting samples from natural rainforests comes with its own set of problems. Continuous rain washes environmental DNA from surfaces, and wind and clouds can be an obstacle to launching drones.

"So we are very curious to see if our sampling method will also prove itself under the extreme conditions in the tropics," Mintchev added.

Protecting and restoring the biosphere is critical to human adaptation and well-being, but the paucity of data on the status and distribution of biodiversity puts these efforts at risk.

DNA that organisms release into the environment, such as environmental DNA, can be used to monitor biodiversity in a scalable way.

However, collecting environmental DNA in terrestrial environments remains challenging due to the many surfaces and potential sources that need to be surveyed and limited accessibility.

The drone design consists of a cage that senses the force of the branch and a tactile control strategy to simultaneously land and maintain the stickers on the upper surface of the branches.

Tests show that the drone can land autonomously on a variety of branches with hardnesses ranging from 1 to 103 Newton/meter (a unit for measuring the force of objects) without prior knowledge of its structure's rigidity.