Dandelions use the wind to disperse their seeds. Researchers at the University of Washington have taken inspiration from the common dandelion to develop a range of wireless sensors that can be distributed by the wind after being dropped from a drone.
Wireless sensors are used to monitor temperature, humidity and other environmental conditions across large geographical areas. Data from these sensors provide unique insights for a variety of applications, including agriculture and monitoring climate change. However, it can be time-consuming and expensive to physically place hundreds of sensors across a large area.
The tiny sensor-carrying device developed by the University of Washington team is about 30 times as heavy as a 1mg dandelion seed but can still travel up to 100 metres in a moderate breeze, once it’s released by a drone. A single device can carry four sensors and shares sensor data up to 60 metres away. Instead of batteries, which can increase weight, the device features tiny solar panels as a power source for its onboard electronics. However, this also means the sensors stop working when the sun goes down, and needs a bit of energy to get started the next morning.
A major challenge for the team was to make the whole device as light as an actual dandelion seed. They first began with a shape that would allow the system to take its time falling to the ground so that it could be tossed around by a breeze. The researchers tested 75 designs to determine the maximum speed a device would have as it fell through the air.
During tests, the prototype devices landed with the solar panels facing upright 95% of the time. The devices are designed to flip over and fall in a consistently upright orientation similar to a dandelion seed, the researchers say.
The sensor-carrying devices were dropped from different heights, either by hand or by drone on campus to measure how far they would travel in the wind. Being battery-free, the device will work until it physically breaks down. Further research is on to make these systems more biodegradable.
Source: The University of Washington
Image: This battery-free device uses solar panels (black rectangles shown here) to power its onboard electronics. (Photo: Mark Stone/University of Washington)
