-
Tiny sensors with a design inspired by dandelion seeds could be scattered to the winds to help track key indicators of climate change and global warming.
-
As the climate crisis continues to intensify, tracking changes in temperature, humidity and other environmental signals across a wide area is useful. But doing so effectively requires dispersing sensors throughout the environment, which can be time-consuming.
-
“Rather than having a person go out and individually place sensors, which can be dangerous in hard-to-reach places where we’d like to do these measurements, we wondered whether it’s possible to build a system that can disperse sensors in the wind,” says Hiram Iyar at the University of Washington in Seattle.
-
Iyar and his colleagues used a laser-powered tool to manufacture devices from polyamide films. Each one weighs 30 milligrams with a diameter of 28 millimeters, and carries an array of small holes through which air can pass to allow it to float in the air like a dandelion seed.
- The discovery, which confirms the common plant among the natural world's best fliers, shows that movement of air around and within its parachute-shaped bundle of bristles enables seeds to travel great distances -- often a kilometer or more, kept afloat entirely by wind power.
- Researchers from the University of Edinburgh carried out experiments to better understand why dandelion seeds fly so well, despite their parachute structure being largely made up of empty space.
- Their study revealed that a ring-shaped air bubble forms as air moves through the bristles, enhancing the drag that slows each seed's descent to the ground.
- This newly found form of air bubble -- which the scientists have named the separated vortex ring -- is physically detached from the bristles and is stabilized by air flowing through it.
- The amount of air flowing through, which is critical for keeping the bubble stable and directly above the seed in flight, is precisely controlled by the spacing of the bristles.
- This flight mechanism of the bristly parachute underpins the seeds' steady flight. It is four times more efficient than what is possible with conventional parachute design, according to the research.
- Researchers suggest that the dandelion's porous parachute might inspire the development of small-scale drones that require little or no power consumption. Such drones could be useful for remote sensing or air pollution monitoring.
- The study, published in Nature, was funded by the Royal Society.
- Dr Cathay Cummins, of the University of Edinburgh's Schools of Biological Sciences and Engineering, who led the study, said: "Taking a closer look at the ingenious structures in nature -- like the dandelion's parachute -- can reveal novel insights. We found a natural solution for flight that minimizes the material and energy costs, which can be applied to engineering of sustainable technology."
- Scientists estimate that this parachute design is around four times more efficient than what is possible with conventional parachute.
- The Parachute structure of dandelion seeds is largely made up of empty space, which always confused scientists – how can it fly so well? Scientists did a lot of simulations and experiments and found that when air is moving through the parachute bristles, a ring-shaped air bubble is formed. It enhances drag and allows the seed to gently descend to the ground. This air bubble, named a separated vortex ring by scientists, is precisely controlled by the air flowing through the bristles, which is controlled by the gap between them. In other words, mechanical properties of the parachute underpin the seeds’ steady flight.
You must be logged in to post a comment.