Scientists ‘beat nature’ by creating the world’s smallest ever flying machine

Researchers from Northwestern University were inspired by the aerodynamic properties of plant seeds to create flying chips that can monitor for pollution

Engineers have created the smallest-ever flying man-made structure: a tiny, moving microchip.

The ‘microfliers’, developed by researchers from Northwestern University, are approximately the size of a grain of sand and do not require a motor or an engine.

Instead, the chip - which can carry sensors, power sources, antennas for wireless communication and can store data - catches flight on the wind akin to the propeller seeds from maple trees, spinning through the air towards the ground.

When the chip is dropped from a height, it will fall at a slow, controlled velocity, which makes it ideal for monitoring air pollution and airborne diseases.

"Our goal was to add winged flight to small-scale electronic systems, with the idea that these capabilities would allow us to distribute highly functional, miniaturised electronic devices to sense the environment for contamination monitoring, population surveillance or disease tracking," said Northwestern's John A. Rogers, who led the device's development.

"We were able to do that using ideas inspired by the biological world. Over the course of billions of years, nature has designed seeds with very sophisticated aerodynamics. We borrowed those design concepts, adapted them and applied them to electronic circuit platforms."

Rogers’ team studied the aerodynamic qualities of several plants’ seeds, drawing inspiration from the tristellateia vine, which has star-shaped seeds, and experimented with various designs in laboratory conditions. The first designs of the tiny craft were made in two-dimensions, bonded onto a slightly stretched rubber substrate.

When the substrate was relaxed, a controlled buckling process caused the wings to ‘pop’ up into a defined three-dimensional form. This meant that the engineers could build semiconductor devices in a conventional manner, which can then be ‘popped up’ like a children’s book.

"We think that we beat nature," Rogers said. "At least in the narrow sense that we have been able to build structures that fall with more stable trajectories and at slower terminal velocities than equivalent seeds that you would see from plants or trees.

“We also were able to build these helicopter flying structures at sizes much smaller than those found in nature".

The researchers suggest that a number of devices could be dropped from planes or buildings to monitor the environment after a chemical spill or in other environmentally hazardous areas, forming a wireless network.

While this could also cause environmental problems, the lab is developing transient electronics that dissolve in water when they are no longer required using degradable polymers, compostable conductors, and a dissolvable integrated circuit chip.

The study, ‘Three-dimensional electronic microfliers inspired by wind-dispersed seed’, is published in Nature.