The potential of battery-free wireless sensors is decidedly greater than expected: by themselves they are able to monitor the trend of temperature, humidity and various other environmental conditions. We are talking about useful and functional tools, which have many fields of application (from agriculture to monitoring climate change). The only downside is the cost. Placing hundreds of wireless sensors in a large area is currently very difficult and expensive.
At least it was before the arrival of an incredible new project just published in the journal Nature.
A team at the University of Washington has developed a small device that can carry more than one sensor at a time while being pushed by the wind. The device is inspired by the seeds of the dandelion, or dandelion: the blowers that disperse the air with the arrival of the first winds. In a certain sense, they also take up its shape, equally delicate and "light".
Sensors in the shape of a dandelion
The new device developed by the team weighs around 30 milligrams, and is capable of traveling up to 100 meters in a moderate breeze.
Once on the ground, take advantage of the help of special ones solar panels to feed and share sensor data (inside there are at least four) up to 60 meters away.
Shyam Gollakota, professor at the Paul G. Allen School of Computer Science & Engineering and author of the project, provided some more information. According to him, this innovative system provides a clear hint on how to implement sensor distribution without increasing prices.
Our prototype suggests you could use a drone to release thousands of these devices in a single drop. They will all be carried by the wind a little differently and you can basically create a network of 1.000 devices with this drop. This is amazing and transformative for the field of sensor deployment, because right now it could take months to manually deploy so many sensors.
Tangible results
In the roadmap that led to the current form, the researchers tested 75 different designs. Alternatives and options have been scrutinized to arrive at the perfect compromise. To keep the structure light, the team chose to use solar panels instead of a classic battery. Based on what emerged from the tests, the devices landed with the solar panels facing vertically 95% of the time, allowing a correct energy recharge.
Sensors trapped in the system
Having no battery, the devices risk not storing energy. And that would essentially mean that after dark the sensors stop working. To solve the problem, the team included a capacitor in the system - a device capable of storing a certain charge overnight. After that another small circuit will be added, which will measure how much energy has been stored and how much is still available.
Each of these small devices relies on a specific transmission method. The goal, in fact, is to wirelessly send sensor data to researchers, so they can analyze it.
The devices will have the task of measuring temperature, humidity, pressure and light. They will send the data until sunset, and then start over the next morning.
Future developments
Among the possible developments, there is the idea of making the systems even more biodegradable.
This is because, as there is no battery, the device will continue to work until it physically breaks. This means that it will end up lost in the ecosystem, too small to be found again. It is therefore better to think of a hypothesis that is not harmful to the environment.
Vikram Iyer, the lead author of the project, is excited about the future.
This is just the first step. There are so many other directions we can take now, such as developing large-scale implementations, creating devices that can change shape as they fall, or even adding a little more mobility so devices can move a turn to the ground to get closer to an area that intrigues us.
