Tiny, Solar-Powered Sensors Fly Through the Air Like Dandelion Seeds

Taking inspiration from floating dandelion seeds, University of Washington researchers developed tiny sensors that measure humidity, air pressure, and light. As these miniature devices float along with the wind, they can provide unique insights into how climate change affects hard-to-reach ecosystems in a warming world, reports Jaime Priest for Cosmos.

The whimsical, circular device is solar powered and does not require batteries. After being released from a drone, the sensors can ride a breeze up to 100 meters, or the length of a football field. Scientists hope that thousands of these tiny wagon wheel–shaped instruments can collect environmental data and monitor humidity or temperature fluctuations, reports Jennifer Walter for Inverse. Details on the new tech were published this month in Nature. 

Engineers made the tiny-but-mighty devices from thin polymer discs, designed in a shape that allowed them to stay in the air for as long as possible. Sensors and electronic components lie in the center of the wheel-shaped gadget and enable it to transmit data up to 60 meters away, per a statement.

“The way dandelion seed structures work is that they have a central point and these little bristles sticking out to slow down their fall. We took a 2-D projection of that to create the base design for our structures,” says study author Vikram Iyer, a University of Washington computer scientist, in a statement. “As we added weight, our bristles started to bend inwards. We added a ring structure to make it more stiff and take up more area to help slow it down.”

Wind Dispersal of Battery-free Wireless Devices

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Each sensor is unique in size, ranges between 10 to 50 milliliters in diameter and weighs about 30 milligrams, Inverse reports. Dandelion seeds, in comparison, weigh one milligram. Just like feathery dandelion seeds, the sensors also land with the solar panels facing upright with 95 percent accuracy, a statement explains. The sensor’s circular structure allows it to tumble and flip, eventually landing in an upright orientation. Researchers tested over 75 different designs before finding the perfect one that maximized its reach, Cosmos reports.

“This is mimicking biology, where variation is actually a feature, rather than a bug,” says study co-author Thomas Daniel, a University of Washington biologist, in a statement. “Plants can’t guarantee that where they grew up this year is going to be good next year, so they have some seeds that can travel farther away to hedge their bets.”

To create the high-tech sensor, researchers replaced heavy batteries with small solar panels strong enough to power the device. However, without a battery pack, the sensor can’t hold a charge and power off when there is no sunlight. So, the team designed the electronics to have a capacitor to store some charge at nighttime. After the disc-like sensors collect data, they transmit it to researchers through backscatter technology, which reflects radio signals back to the original source.

Because the sensors are intentional scattered throughout an environment, one potential drawback of the technology is that they are not made with biodegradable material. The team plans to explore how to make a more environmentally-friendly design to minimize microplastic accumulation in an ecosystem.

“This is just the first step, which is why it’s so exciting,” Iyer says in a statement. “There are so many other directions we can take now — such as developing larger-scale deployments, creating devices that can change shape as they fall, or even adding some more mobility so that the devices can move around once they are on the ground to get closer to an area we’re curious about.”

Elizabeth Gamillo | | READ MORE

Elizabeth Gamillo is a daily correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.