'Flying' microchips could ride the wind to track air pollution

Researchers have created a winged microchip around the size of a sand grain that may be the smallest flying device yet made, Vice has reported. They're designed to be carried around by the wind and could be used in numerous applications including disease and air pollution tracking, according to a paper published by Nature. At the same time, they could be made from biodegradable materials to prevent environmental contamination.

The design of the flyers was inspired by spinning seeds from cottonwood and other trees. Those fall slowly by spinning like helicopters so they can be picked up by the wind and spread a long distance from the tree, increasing the range of the species.

The team from Northwest University ran with that idea but made it better, and smaller. "We think we've beaten biology... we've been able to build structures that fall in a more stable trajectory at slower terminal velocities than equivalent seeds," said lead Professor John A. Rogers. "The other thing... was that we were able to make these helicopter flyer structures that are much smaller than seeds you would see in the natural world."

They're not so small that the aerodynamics starts to break down, though. "All of the advantages of the helicopter design begin to disappear below a certain length scale, so we pushed it all the way, as far as you can go or as physics would allow," Rogers told Vice. "Below that size scale, everything looks and falls like a sphere."

The devices are also large enough to carry electronics, sensors and power sources. The team tested multiple versions that could carry payloads like antenna so that they could wireless communicate with a smartphone or each other. Other sensors could monitor things like air acidity, water quality and solar radiation.

The flyers are still concepts right now and not ready to deploy into the atmosphere, but the team plans to expand their findings with different designs. Key to that is the use of biodegradable materials so they wouldn't persist in the environment.

"We don't think about these devices... as a permanent monitoring componentry but rather temporary ones that are addressing a particular need that’s of finite time duration," Rogers said. “That's the way that we're envisioning things currently: you monitor for a month and then the devices die out, dissolve, and disappear, and maybe you have to redeploy them."