Engineers at Northwestern University have built what they claim is the world's smallest human-made flying structure, the size of a grain of sand — by giving a microchip wings.
“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, miniaturized electronic devices to sense the environment for contamination monitoring, population surveillance or disease tracking," explains John A. Rogers, who led the team responsible for developing the tiny machine.
“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."
The ultra-compact device isn't exactly a drone, however, and it doesn't exactly fly — at least not under its own power. Inspired by the propeller-like seeds of the maple tree, the chip's wings catch the air and spin like a helicopter — slowing its descent and allowing it to ride the wind to a more far-flung destination.
“Evolution was likely the driving force for the sophisticated aerodynamic properties exhibited by many classes of seeds," Rogers explains. "These biological structures are designed to fall slowly and in a controlled manner, so they can interact with wind patterns for the longest-possible period of time. This feature maximizes lateral distribution via purely passive, airborne mechanisms."
"We think that we beat nature. 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 team is hoping that the technology could be used to carry a useful payload including a power source, sensors, memory, and even an antenna — meaning a selection could be sprinkled from an aircraft and provide readings over a wide area. Prototypes have been built capable of detecting particulates in the air, measuring the pH level of water, and checking sunlight exposure.
Another version of the flying microchips could solve the post-distribution waste problem, too. "We fabricate such physically transient electronics systems using degradable polymers, compostable conductors and dissolvable integrated circuit chips that naturally vanish into environmentally benign end products when exposed to water," Roger claims. "We recognize that recovery of large collections of microfliers might be difficult. To address this concern, these environmentally resorbable versions dissolve naturally and harmlessly."
The team's work has been published under closed-access terms in the journal Nature.