28-09-2021 | By Sam Brown
Recently, researchers have created miniaturised sensors that can fly in the wind, rotate, and generate sensory data all in the space of a few millimetres. What challenges do environmental sensors face, what did the researchers develop, and could it present its own environmental challenges?
Whether it’s to monitor air quality, track vehicle usage, or determine the overall cloud cover of a country, IoT environmental sensors are becoming increasingly popular. Of course, such systems are only valuable when combined with big data systems that use AI and other algorithms to make sense of the data produced by sensors. Furthermore, big data systems are only practical when working with large amounts of data, meaning that they are needed in large numbers for environmental IoT sensors to be practical.
This presents engineers who design IoT sensors with a range of challenges seldom seen in the home or office. The first significant challenge is finding a suitable power source; remote sensors will most likely not access mains power. As such, remote IoT are almost always required to store their own power (with the use of batteries) or generate their own power with the help of energy harvesters.
The second challenge involved with environmental IoT sensors is the need for many widely disbursed sensors to provide a large coverage area. Manufacturing ten thousand sensors is a relatively easy task, but manually installing each sensor can be time-consuming.
Recently, researchers from Northwestern University have created a new device that not only holds electronic components but can glide through the air. These devices are extraordinarily small, measuring just a few millimetres and integrating all the components needed to create functional IoT sensors.
The devices have been inspired by sycamore seeds which have a seed attached to a blade. When these seeds fall in the wind, they rotate rapidly, which slows down their descent. This is critical for the seeds to maximise their dispersion distance from the mother tree, and this concept has been transposed to the new IoT sensors.
When the newly developed devices fall, they too rotate and slow down their rate of falling. Their unique design also enables them to be carried at great distances in the wind providing a potential mechanism for mass dispersal.
The devices themselves integrate energy harvesters that enable them to be powered from naturally occurring energy and memory storage for data and an antenna to facilitate data transfer to other devices. Furthermore, some of the devices were outfitted with sensors designed to detect particulates in the air, while others incorporated pH sensors for measuring water quality in the atmosphere.
There is no doubt that what the researchers have demonstrated is absolutely brilliant; tiny devices can flow with the wind and take sensory measurements while being accessed remotely. However, there is a cause for concern with the concept of mass producing devices that are left to litter the environment.
According to the researchers, this worry has been planned for using electronics that can dissolve in water (this has already been demonstrated by the same team). As such, all devices eventually break down naturally in the environment in a mechanism similar to biodegradable parts.
However, not all aspects of electronics can easily be recycled, and any remaining plastics or metallic parts could pose health risks to living organisms. Like how microplastics are becoming a challenge, having thousands of decomposing electronics containing metals and plastics could be met with severe backlash from the public and governing regulatory bodies.
Another problem that the mass deployment of such sensors presents is their potential to invade the privacy of unsuspecting individuals. The idea of such sensors is that they can be dropped from a plane and cover a large area for monitoring. But, if such a deployment was done over a populated area, then there is a chance that these sensors could be used maliciously.