Researchers at the University of Tampere, Finland, and the University of Pittsburgh, USA, have developed a tiny robot that replicates the aerial dance of falling maple seeds. In the future, the robot could be used for real-time environmental monitoring or small sample delivery in difficult-to-access terrain such as deserts, mountains, cliffs, or the open ocean. The technology could be a game changer in areas such as search and rescue, endangered species research, or infrastructure monitoring.
At Tampere University, Professor Hao Zheng and PhD researcher Jianfeng Yang work at the interface of physics, soft mechanics and materials engineering in the Light Robots research group. They have taken inspiration from nature and designed polymer gliding structures that can be controlled using light.
Now, Zeng and Yang, together with Professor M. Ravi Shankar of the University of Pittsburgh Swanson School of Engineering, have used light-activated smart materials to control the gliding mode of artificial maple seeds. In nature, maple trees disperse to new growth points with the help of wings located in samaras or dried fruits. The wings rotate as the seeds fall, helping them glide in gentle winds. The configuration of these wings defines the glide path.
According to the researchers, artificial maple seeds can be actively controlled using light and can achieve different glide trajectories by actively adjusting their wind dispersal process. In the future, they could also be equipped with a variety of microsensors for environmental monitoring or used to deliver small soil samples, for example.
High-tech robots surpass natural seeds in adaptability
The researchers were inspired by the diverse gliding seeds of Finnish trees, each of which exhibits a unique and fascinating flight pattern. Their fundamental question was whether the structure of these seeds could be replicated using artificial materials to achieve similar aerial grace controlled by light.
“The small light-controlled robot is designed to be released into the atmosphere, utilizing passive flight to disperse widely through interaction with surrounding airflow. It is equipped with GPS and various sensors to monitor local environmental indicators such as pH levels and heavy metal concentrations in real time,” explains Yang.
Inspired by the natural maple samara, the team created an azobenzene-based photomorphic liquid crystal elastomer that achieves reversible photochemical modifications to finely tune its aerodynamic properties.
“Artificial maple seeds outperform natural seeds in terms of adjustable terminal speed, rotational speed and hovering position, improving wind-driven long-distance locomotion through self-rotation,” Zeng said.
In early 2023, Zeng and Yang launched their first dandelion seed-like mini robot within the Flying Aero-robots project based on the Light Responsive Materials Assembly — FAIRY. The project, funded by the Finnish Research Council, will begin in September 2021 and continue until August 2026.
“Whether it’s seeds, bacteria or insects, nature provides us with clever templates for moving, feeding and reproducing, often through simple but surprisingly functional mechanical designs,” explains Shankar.
“Advances in photosensitive materials allow us to direct mechanical behavior at a near-molecular level. We now have the potential to create microrobots, drones and probes that can not only reach otherwise inaccessible areas, but also convey critical information to their users. This could be a game changer in areas such as search and rescue, studying endangered or invasive species, or monitoring infrastructure,” he added.
