Amazing airborne microchips are the smallest human-built objects to take flight

Like helicopter seeds slowly falling to the ground, these newly created “microfliers” capture the wind for controlled, powered flight.

New research in Nature claims the old adage of not wasting time trying to reinvent the wheel. Engineers at Northwestern University in Evanston, Illinois heavily borrowed from nature to develop microchips capable of passive flight. Called “microfliers”, the tiny devices surf the breeze as they fall. and take advantage of the powers of rotation to fall in a slow and controlled manner.

The process is like helicopter seeds falling from a maple tree, and it’s no coincidence. The team, led by engineer John Rogers, studied various plants and trees to understand how nature, after millions of years of evolution, stumbled upon some rather excellent solutions for distributing seeds. Windblown Seeds tend to use one of four different strategies: helicopters, floats (or spinners), gliders, and paratroopers.

“Evolution was probably the driving force behind the sophisticated aerodynamic properties exhibited by many classes of seeds,” Rogers explained in a press release. “These biological structures are designed to fall slowly and in a controlled manner, so that they can interact with the winds for the longest period of time possible. This feature maximizes lateral distribution via purely passive airborne mechanisms.

The aim of the project was to find efficient ways to distribute functional miniaturized electronic devices and do it en masse. Dropping thousands of microflyers from airplanes or high-rise buildings could provide unique means of monitoring the environment, such as pollution, toxic spills, and the spread of disease. The modified microfliers could form powerful interconnected networks made up of hundreds or thousands of nodes, or communicate wirelessly with external devices, acting as sensors in the Internet of Things. The potential applications are virtually limitless.

After performing tests, the researchers found that the helicopter and spinning seeds performed better, especially the seeds of the tristellateia plant. The winged bladed seeds of this flowering vine straddle the wind, slowly descending as it turns. The team built a bunch of different tristellateia-like microfliers, including one with three wings instead of the usual five. The microfliers also varied in size, including versions as tiny as pebbles and even single grains of sand (the smaller versions were 500 microns wide).

Computer simulations have shown how air can circulate around the various devices, and wind tunnels demonstrated how aerodynamics were influenced by design adjustments, such as changes in wing diameter, structure and type. Tests have shown that rotational motion is key, as it serves to stabilize and slow the descent of the object, allowing it to spread fafrom its point of disembarkation. A slow descent is also beneficial in that it allows the aircraft to extend its in-flight surveillance functions. Impressive, the team says they came up with designs that rival and maybe improve the best that nature has to offer.

“We think we’re beating nature,” Rogers said. “At least in the narrow sense that we were able to build structures that fall with more stable trajectories and at slower terminal velocities than the equivalent seeds you would see from plants or trees.”

In addition, some of their microfliers were considerably smaller than those found in nature.

“This is important because device miniaturization represents the dominant development trajectory in the electronics industry, where sensors, radios, batteries and other components can be built in ever smaller dimensions,” Rogers added.

Another key part of a successful controlled descent is a little weight. Without a little bulk, the flyer would be out of control, and without a low center of gravity, it couldn’t turn. The good news is that these devices carry weight in the form of built-in components, such as microchips, solar cells (or batteries), and antennas. Collectively, these add-ons would provide the brain microflinder with power and wireless communications.

“This research provides a fundamental understanding of these engineering systems and poses some questions for future studies,” wrote E. Farrell Helbling, an electrical and computer engineer from the University of Ithaca who was not involved in the study, in an accompanying News & Views article. Specifically, said said, future work should consider “how the wind affects the aerodynamics of aviators ”, because the researchers, while taking into account various environmental factors, have yet to study the wind in more detail. In addition, “the authors’ results focus on helicopter and weather vane-type dispersion methods, which leaves the design of parachute and glider-type aviators for future study and raises questions about possible trade-offs between spatial scope, payload, etc. ”Helbling wrote.

In testing, the team demonstrated a 2-inch (5 cm) microflower capable of monitoring particles in the air as it slowly descended. The team is considering future versions capable of monitoring water quality with pH sensors and sun exposure with photodetectors. Practical applications include tracking chemical or oil spills, air pollution at different altitudes, and, perhaps more worryingly, human movement.

Indeed, the ethical and legal ramifications of this technology will have to beto avoid potential abuse, such as surreptitious tracking of people. The team is also aware that the microfliers could eventually become a form of litter or pollutant themselves.It is. To this end, they are working on versions that either dissolve in water or degrade naturally over time. They are also looking to make microfliers that can actively fly, which will be considerably more difficult.