The “winged microchip” is the smallest flying device built by humans and has a wide range of applications. One of the properties of plants is that they cannot move. However, they need to find a way to spread their seeds over as large an area as possible, and evolution has developed many ways of making them fly – just think of the dandelion’s flying hairs or the maple leaf. And we are used to the fact that what works in nature will sooner or later work for us humans when we think about creating different devices. In essence, we have the world’s smallest man-made flying machine, which in some ways is even better than its biological inspiration.
The grain-of-sand-sized device, the microflier, consists of two main parts: a tiny circuit and wings, and the potential applications are vast — by releasing a lot of these fibres into the air, you can test for air pollution, airborne infections and various forms of environmental contamination, and do so far more efficiently than current solutions. The researchers have tried several naturally occurring solutions to ensure that the device can be dropped from a height and float down in a controlled manner, while covering as large an area as possible and staying in the air as long as possible. In addition, the micro-fibre can be equipped with a range of miniature technological devices, such as sensors, an energy source powered by the environment, antennas for wireless communication and a built-in memory.
The selected solutions were then tested using computer modelling to see how air flows around the wings. Finally, these were used to produce test versions, inspired by pop-up children’s books. This ‘pop-up’ method made it possible to create a spatial structure from planar elements, which is important because electronic devices are available as a sheet. Eventually, several structures were created, some of which even beat nature’s solutions, as the artificial structures fall in a more stable trajectory, at a lower terminal velocity, and are much smaller than naturally occurring seeds and leaves.
Devices have also been tested that are equipped with sensors, a power source, antennas that can transmit data to a smartphone or tablet, and built-in memory. In the laboratory, the devices have been used to test for the presence of different particles, but also to measure water quality using a pH sensor and sunlight at different wavelengths using light sensors. The method could be used to investigate the regeneration of the environment following an industrial accident, or even to test air pollution at different altitudes.
At present, similar measurements are carried out with larger structures that try to cover the area to be tested at several points. With microfibres, however, a large number of miniaturised sensors would be distributed at high spatial density over more extensive areas, while forming a wireless network. To reduce the environmental impact, the devices would be made of materials that are easily degradable in water. A video of this otherwise quite spectacular process can be viewed at this link.