biomimetics great designs: ones we can copy (Introduction)

by David Turell , Wednesday, June 01, 2022, 19:14 (696 days ago) @ David Turell

Dandelion seed dispersal:

https://www.sciencedaily.com/releases/2022/06/220601111753.htm

"Known for their fluffiness and uncanny ability to help children tell the time, dandelions provide essential early-Spring food for pollinators like bees, birds, butterflies, and moths.

"Their seeds are some of the best flyers in nature, catching the wind and spreading as far as 100 kilometres. Part of how they do this is by tuning their flight depending on the weather. (my bold)

"Each dandelion seed is tethered by a thin tube to around 100 bristles, which form the parachute-like structure. When seeds break free from the flower head, these bundles of hairs catch the wind and carry their seeds. This hairy parachute closes when the air is humid, which often means the wind is weak. In drier, more windy conditions, dandelions widen their parachutes to better catch the wind so the seeds can fly freely.

"Their work, published in Nature Communications, found the seed-carrying parachutes open and close using something like actuators -- devices that convert signals into movement -- without using energy.

"The centre of the parachutes senses the humidity of their immediate environment by absorbing water molecules from the air. Responding to these humidity signals, they 'decide' to either open their parachutes and fly away, or to close their parachutes and stay put.

"They also found that the actuator has a unique radial, tube-like design to which the parachute hairs are attached to ensure simultaneous movement. The actuator changes its shape to either open or close their parachutes.

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"They found that parachute opening is modulated by the level of humidity in the atmosphere: higher humidity triggered swelling in the actuator and mechanical movement of hairs upwards, which closed the parachutes. Some regions of the actuator swelled noticeably, whereas others, such as the vasculature, barely changed. They observed that the actuator shape change was caused by uptake and release of water droplets, creating a crease in the area the parachute hairs are attached.

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"Plant structures can serve as important inspiration for soft robotics as, like plants, these robots don't use joints or rigid parts to move appendages. Finding out how dandelion parachutes respond to their environment by moving many appendages simultaneously could help engineers create robots that move multiple fingers and arms with very simple yet functional designs. The way the dandelion actuator changes shape in some regions but not others can also teach us about mechanisms of shaping and movement in soft robots and biological tissues."

Comment: this seems to be a physical reaction to water vapor, but it is possible some biochemical reactions may be helping yet to be discovered. Teh plant doesn't know it needs good seed dispersal, but a designer obviously would recognize the need. Another biomimetic design to help our engineers.