Inspired by nature, researchers have recently developed a new sensor platform that floats in the wind to travel far while recording a wide range of environmental data. What challenges does monitoring the environment present, what did the researchers develop, and what challenges do such sensors face?

What challenges does monitoring the environment present?

There is no doubt that human activity affects the environment, whether it is the production of acid rain from burning coal, the poisoning of rivers from mining operations, or the extinction of life when clearing large areas of forest land. But in order to be able to better protect our environment, we first need to truly understand what is going on, and this can be done with data.

Monitoring the general climate is easy enough with the use of weather stations and satellites, but trying to monitor the condition of a forest in real-time can be highly challenging. For one, there is no infrastructure to power sensors and provide remote communication, meaning that services may need to be installed. The second problem is that places that are too remote for services will require professionals to locate key areas, install sensors, and then frequently return to download whatever data has been gathered. Long story short, nature is extremely hard to access from a data point of view, and the ever-changing landscape combined with its sheer size makes it an unforgiving place for electronics.

Autonomous drones are another solution to monitoring the environment in remote locations, and their ability to navigate in all three dimensions allows for operation almost anywhere. However, drones can only go so far, and those suitable for covering hundreds of square miles would not be able to hover in one place to take readings (it would most likely be a plane-type where it constantly moves). Thus, drones are useful for sweeping scans but not for long-term measurements of a particular spot.

Researchers create a sensor that drifts in the wind

To solve the challenges of sensor deployment in the environment, a team of researchers turned their attention to dandelion seeds and how they can carry themselves for many miles via wind. To recreate this behaviour, the researchers from the University of Washington created a device that only weighs 30mg and includes a microcontroller, various sensors, an antenna, and a small solar cell, all mounted onto a disc-shaped wing.

When dropped from a drone, the sensor can travel up to 100 meters in the wind, and the wing design ensures the sensor lands upright 95% of the time. The wing is made using a laser cutter while the electronics are attached to a flexible PCB that is folded onto itself to create a very compact structure.

The device is constructed entirely from off-the-shelf components, which significantly improves its commercial viability, and the lack of a battery helps to reduce the weight considerably. A small capacitor stores charge during the day, which can then be used to power the device at night, and the use of backscatter radio communications allows the device to create a mesh network with other devices.

What challenges do such sensors face?

The device that has been developed is currently more of a concept than a prototype, and there are several challenges that it faces which must be addressed before it can be deployed.

The first is that a drone dropping 1000 sensors from the same location would most likely see all sensors falling in the same area. In reality, dandelion seeds include variation, ensuring that each seed is carried in a unique direction and distance to maximise coverage. Thus, the researchers would need to deploy variation amongst each sensor so that each one behaves differently in the wind.

The second is that the electronics used in the sensor are not biodegradable and would quickly pollute the surrounding area. Such sensors will take thousands of years to break down due to silicon and plastics, and many of these sensors will likely be consumed by wildlife. Thus, deploying a drone with 1000 sensors could cause long-lasting damage whose sensor data would not be able to justify the damage done.

Overall, the use of microsensors deployed in mass could be a great way to record data from large land areas, but their environmental impact would be devastating if not built using biodegradable circuits.