Researchers from Tampere University, Finland, and the University of Pittsburgh, U.S., have developed a tiny robot replicating the aerial dance of falling maple seeds. In the future, this robot could be used for real-time environmental monitoring or delivery of small samples even in inaccessible terrain such as deserts, mountains or cliffs, or the open sea.

This technology could be a game changer for fields such as search-and-rescue, endangered species studies, or infrastructure monitoring.

At Tampere University, Professor Hao Zeng and Doctoral Researcher Jianfeng Yang work at the interface between physics, soft mechanics, and material engineering in their Light Robots research group. They have drawn inspiration from nature to design polymeric gliding structures that can be controlled using light.

Now, Zeng and Yang, with Professor M. Ravi Shankar, from the University of Pittsburgh utilized a light-activated smart material to control the gliding mode of an artificial maple seed.

In nature, maple disperse to new growth sites with the help of flying wings in their samara, or dry fruit. The wings help the seed to rotate as it falls, allowing it to glide in a gentle breeze. The configuration of these wings defines their glide path.

The article “Photochemical Responsive Polymer Films Enable Tunable Gliding Flight” by Jianfeng Yang, M. Ravi Shankar, and Hao Zeng was published in Nature Communications on 1 June, 2024.

According to the researchers, the artificial maple seed can be actively controlled using light, where its dispersal in the wind can be actively tuned to achieve a range of gliding trajectories. In the future, it can also be equipped with various microsensors for environmental monitoring or be used to deliver, for example, small samples of soil.

Hi-tec robot beats natural seed in adaptability

The researchers were inspired by the variety of gliding seeds of Finnish trees, each exhibiting a unique and mesmerizing flight pattern. Their fundamental question was whether the structure of these seeds could be recreated using artificial materials to achieve a similar airborne elegance controlled by light.

“The tiny light-controlled robots are designed to be released into the atmosphere, utilizing passive flight to disperse widely through interactions with surrounding airflows. Equipped with GPS and various sensors, they can provide real-time monitoring of local environmental indicators like pH levels and heavy metal concentrations,” explains Yang.

Inspired by natural maple samara, the team created an azobenzene-based light-deformable liquid crystal elastomer that achieves reversible photochemical deformation to finely tune the aerodynamic properties.

“The artificial maple seeds outperform their natural counterparts in adjustable terminal velocity, rotation rate, and hovering positions, enhancing wind-assisted long-distance travel through self-rotation,” says Zeng.

In the beginning of 2023 Zeng and Yang released their first, dandelion seed like mini robot within the project Flying Aero-robots based on Light Responsive Materials Assembly—FAIRY. The project started in September 2021, and will continue until August 2026.

“Whether it is seeds or bacteria or insects, nature provides them with clever templates to move, feed and reproduce. Often this comes via a simple, but remarkably functional, mechanical design,” Shankar explains.

“Thanks to advances in materials that are photosensitive, we are able to dictate mechanical behavior at almost the molecular level. We now have the potential to create micro-robots, drones, and probes that can not only reach inaccessible areas but also relay critical information to the user. This could be a game changer for fields such as search-and-rescue, endangered or invasive species studies, or infrastructure monitoring,” he adds.

It is widely accepted that biological interactions are stronger or more important in generating and maintaining biodiversity in the tropics than in temperate regions. However, this hypothesis has not been fully tested in ecology and evolutionary biology.

In a study published in Nature Ecology and Evolution, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences have provided strong support for this central prediction by examining phytochemical diversity and herbivory in 60 tree communities ranging from species-rich tropical rainforests to species-poor subalpine forests.

The researchers investigated tree communities in Yunnan, one of the world’s floristic hotspots, which contains an elevation gradient from tropical rainforest to subtropical forest to subalpine forest within a relatively short distance. In 2011 and 2012, they established 60 long-term forest inventory plots ranging from species-rich tropical rainforest to species-poor subalpine forest along the gradient.

Using community metabolomic approaches, they tested the predictions that phytochemical diversity is higher within and among communities in tropical forests as compared to less species-rich subtropical and subalpine forests. They also measured herbivore damage and leaf specialization.

Combining these data, they tested the prediction that these variables are higher in the tropics. They then quantified the phylogenetic signal in the phytochemical similarity between species to test whether closely related species diverged more in their phytochemicals than expected.

They found that phytochemical diversity was higher within tropical tree communities compared to subtropical and subalpine communities. Along with increased alpha and beta phytochemical diversity in leaves in tropical tree communities, they found an increase in leaf herbivory and the degree of specialized herbivory in the tropics. Furthermore, herbivory pressure and specialization were highest in the tropics.

The researchers then constructed a phylogeny including all species in their system and quantified phylogenetic signal in phytochemical similarity. They found little phylogenetic signal in tree phytochemical similarity, suggesting rapid divergence among closely related species.

The results also highlight multiple dimensions of tropical biodiversity that are often unquantified and of value to human society, but which are threatened by ongoing global change. Tropical forests not only contain more species than temperate forests, but also spectacular levels of phytochemical diversity. There are likely numerous abiotic covariates (e.g., temperature and precipitation) and biotic covariates (e.g., herbivores, pathogens, neighborhood composition and diversity) that may be associated with phytochemical diversity and cannot be clearly separated to elucidate specific mechanisms.

“Our study provides multiple lines of evidence from entire tree communities from the tropics to the subalpine that biotic interactions are likely to play an increasingly important role in generating and maintaining tree diversity at lower and lower latitudes,” said Yang Jie of XTBG.

Nightmare material or truly man’s best friend? A team of researchers equipped a dog-like quadruped robot with a mechanized arm that takes air samples from potentially treacherous situations, such as an abandoned building or fire. The robot dog walks samples to a person who screens them for potentially hazardous compounds, says the team that published its study in Analytical Chemistry. While the system needs further refinement, demonstrations show its potential value in dangerous conditions.

Testing the air for dangerous chemicals in risky workplaces or after an accident, such as a fire, is an important but very dangerous task for scientists and technicians. To keep humans out of harm’s way, Bin Hu and colleagues are developing mobile detection systems for hazardous gases and volatile organic compounds (VOCs) by building remote-controlled sampling devices like aerial drones and tiny remotely operated ships.

The team’s latest entry into this mechanical menagerie is a dog-like robot with an articulated testing arm mounted on its back. The independently controlled arm is loaded with three needle trap devices (NTDs) that can collect air samples at any point during the robot’s terrestrial mission.

The researchers test-drove their four-legged “lab” through a variety of inaccessible environments, including a garbage disposal plant, sewer system, gasoline fireground and chemical warehouse, to sample the air for hazardous VOCs. While the robot had trouble navigating effectively in rainy and snowy weather, it collected air samples and returned them to the portable mass spectrometer (MS) for onsite analysis in less time than it would take to transfer the samples to an off-site laboratory—and without putting a technician in a dangerous environment.

The researchers say the robot-MS system represents a “smart” and safer approach for detecting potentially harmful compounds.