Dandelion Seeds Inspire Lightweight Sensors for Mass Networks

Setting up sensor networks can be expensive and time consuming. A new project from the University of Washington has turned to nature for solutions.

Autor*in Mark Newton, 03.23.22

Translation Sarah-Indra Jungblut:

Remote sensing is quickly becoming the backbone of climate and conservation research, as well as the next generation of agriculture. By placing sophisticated sensors around an area of interest, researchers and others can gleam reams of important information without needing to be permanently in the field. 

However, although sensors can greatly reduce logistical burdens, they are not entirely free from them. The locations for sensors must be selected, and then the equipment installed. Some may require more bulky technology, such as large batteries. Placing such sensors takes time, while manpower and costs may limit the amount of sensors that can be practically used.

A research team at the University of Washington has been exploring methods of creating mass sensor networks quickly and conveniently. To realise their goals, they took inspiration from the humble dandelion.

Dandelions have become hated weeds for many farmers, and the key to this sour relationship is their ability to spread their seeds over relatively vast distances. By mimicking the light tendrils (or pappus) of a dandelion seed, the team has created environmental sensors that can be dispersed into the wind across a wide area..

The sensor they have developed is about 30 times heavier than a 1 milligram seed, requiring its ‘pappus’ to be larger and more rigid. However, the sensors can still travel an impressive distance even on a moderate breeze. Testing on the university campus has shown that the dandelion sensors can float up to 100 metres from their release point. Varying the height of the release point, affects the distance travelled. Once on the ground, the device, which can hold up to four separate sensors, can gather information from within a 60 metre radius.

The idea would be to release these sensors, for example from a drone, to rapidly establish a sensor network over areas the size of a football field. Senior author of the study, Shyam Gollakota, a UW professor in the Paul G. Allen School of Computer Science & Engineering stated:

“We show that you can use off-the-shelf components to create tiny things. 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.”

Sensors on the Wind

To keep the weight down, the team experimented with over 75 different designs to find the one which kept the ‘terminal velocity’ – or maximum speed of which the sensor fell – to a minimum. Additionally, the sensors do not use batteries, instead they are powered by small, lighter solar panels. However, This approach does create some additional challenges. The panel needs to land the right way up to charge the device, while the sensors cannot function at night. Luckily, the sensors are specifically designed to flip over to the right orientation, meaning 95 percent land the correct way up.

A lack of battery also means the sensors need more power to start up in the morning. To partly overcome this issue, the sensor includes a capacitor which can store a little charge overnight.

Once in position and charged, the sensors can gather information concerning temperature, humidity, pressure and light, which is wirelessly sent back to researchers via backscatter, a method of sending information by reflecting transmitted signals.

But, the design still needs to be refined. Currently, the team is also looking at altering the shapes of individual sensors to create more variation in travel distance and pattern, meaning the sensors will become more widely dispersed. Once again, the team has taken direct inspiration from nature. Co-author Thomas Daniel, a UW professor of biology explained:

“This is mimicking biology, where variation is actually a feature, rather than a bug. 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.”

Eventually, it may even be possible to create sensors that can move around once they hit the ground, allowing them to get even closer to specific areas of interest.

However, there is one major downside to this approach. With such a large number of sensors being spread over a wide area, it will almost be impossible to retrieve them all. Their lack of battery means they can continue to function long term, but the team is also looking at ways of making the sensors more biodegradable.

In recent years, sensors have taken on an increasingly important role in scientific and environmental research. However, their utility is not limited to universities and other research institutions. The drop in cost of sensor components has led to a surge in citizen science projects, in which normal people donate their time and effort to help conduct mass research. Much of these citizen science projects also ties into themes of civic technology, a topic RESET covered at length in our last Special Feature.

How Sensors on Walls and Balconies Can Help Citizens Clean Up Air Pollution

The air in our cities is polluted. With sensors, citizens can collect measurements, allowing them to uncover sources and build up political pressure.

Non-Invasive Ultra-Thin Needle Sensors Could Power the Precision Farming of the Future

Agri-tech researchers have taken inspiration from medical science to create microneedles that monitor the health of crops.

Can Civic Technology Help You Fix Your City from Your Smartphone?

All too often, living in a city can make you feel like a passive bystander. But new civic technology is aiming to make it easier than ever to get involved and have your voice heard.

Torge Peters/ Studio Nørden
Citizen Science – Everyday People Supporting Scientific Research

Counting birds, analysing satellite images, measuring air values - many organisations and research institutions rely on citizen support for research work. New digital tools make it even easier for lay researchers to contribute to new findings.

Torge Peters/ Studio Nørden
Civic Tech: Citizens Drive Environmental and Climate Protection with Public Data, Apps and Platforms

With citizen-owned digital tools, environmental data and government knowledge can become part of the common good and starting point for change.

Cheap Sensors Provide Missing Air Quality Data in African Cities

Calibrated low-cost sensors in Kinshasa and Brazzaville provide new information on pollution and help scientists model a way to improve access to air quality data.

Saildrone: The Unmanned Research Drones Looking to Survey Every Square Mile of Ocean

Drones are not merely limited to the skies, with sophisticated unmanned vehicles now also able to take to the water - sailing the globe automatically for months at a time and gathering data on the health of our seas and oceans.