The placement of environmental sensors across large areas, such as agricultural fields or forests, can be a time- and cost-intensive task. Inspired by the wind-blown dispersal of dandelion seeds, University of Washington researchers have designed a wireless, battery-free sensor that can be transported and deposited over significant stretches by hitchhiking with prevailing winds.

The sensor-carrying device is about 30 times as heavy as a 1 mg dandelion seed but can still travel up to 100 m in a moderate breeze, about the length of a football field, after its release by drone. The device contains at least four sensors, and upon landing uses onboard solar panels to power electronics and transmit sensor data up to 60 m distant. A tiny capacitor embedded in the sensor system stores some charge at night and activates the sensor at sunrise.

“We show that you can use off-the-shelf components to create tiny things," said researcher Shyam Gollakota. "Our prototype suggests that you could use a drone to release thousands of these devices in a single drop. They’ll all be carried by the wind a little differently, and basically you can create a 1,000-device network with this one drop. This is amazing and transformational for the field of deploying sensors, because right now it could take months to manually deploy this many sensors.”

The battery-free device uses solar panels (black rectangles) to power onboard electronics. Source: Mark Stone/University of Washington

The dandelion-inspired structures described in Nature were demonstrated to reach their final destination with the solar panels facing upright 95% of the time. The drone-delivered sensors could find application in monitoring temperature, humidity, pressure and other environmental parameters.

The next step is to engineer biodegradable components to alleviate the environmental impact of electronic component input on terrestrial ecosystems.