Engineered magic: wooden seed carriers

Geometric design and engineering of biodegradable materials could improve versatility, efficiency of aerial seeding

How seeds implant themselves in soil can seem magical. Take some varieties of Erodium, whose five-petalled flowers of purple, pink or white look like geraniums. The seed of these plants is carried inside a thin, tightly wound stalk. During rain or high humidity, the corkscrew-like stalk unwinds and twists the seed into the soil, where it can take root and is safe from hungry birds and harsh environmental conditions.

Inspired by Erodium’s magic, Lining Yao, the Cooper-Siegel Assistant Professor of Human-Computer Interaction at Carnegie Mellon University, worked with a team of collaborators to engineer a biodegradable seed carrier referred to as E-seed. Their seed carrier, fashioned from wood veneer, could enable aerial seeding of difficult-to-access areas, and could be used for a variety of seeds or fertilizers and adapted to many different environments. It’s an idea that Yao, the daughter of part-time farmers, has pondered since she was a Ph.D. student at MIT in the mid-2010s.

“Seed burial has been heavily studied for decades in terms of mechanics, physics and materials science, but until now, no one has created an engineering equivalent,” said Yao, director of the Morphing Matter Lab in the School of Computer Science’s Human-Computer Interaction Institute. “The seed carrier research has been particularly rewarding because of its potential social impact. We get excited about things that could have a beneficial effect on nature.”

The team’s research appeared in the February issue of Nature.

Danli Luo, a former research assistant at the Morphing Matter Lab and the lead author of the Nature paper, said design and construction of the seed carrier were inspired by the self-burying mechanism that Erodium evolved as it adapted to arid climates.

Erodium’s stalk forms a tightly wound, seed-carrying body with a long, curved tail at the top. When it begins to unwind, the twisting tail engages with the ground, causing the seed carrier to push itself upright. Further unwinding creates torque to drill down into the ground, burying the seed.

“Making E-seed through digital design and fabrication methods is crucial for our long-term goals,” said Guanyun Wang, a former postdoctoral researcher in the Morphing Matter Lab who continued on the project after assuming a faculty position at Zhejiang University. In addition to seeds, the researchers demonstrated they could use the carriers to deliver nematodes (worms used as natural pesticides), fertilizers and fungi. Work is also underway to adapt them for planting seedlings.

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