Engineering: Seed-inspired microdevices that ride the wind

Flying devices with designs inspired by wind-dispersed plant seeds, which may have applications in environmental monitoring or communications, are described in Nature. The fliers can carry active electronic payloads, establishing a new potential range of battery-free wireless devices.

Plant seeds come in a range of shapes and sizes, some of which facilitate wind dispersal to distribute genetic material and to propagate the species. The shapes fall into four broad categories: parachuters, such as those of the dandelion (Taraxacum officinale); gliders, such as those of the Javan cucumber (Alsomitra macrocarpa); helicopters, such as those of the box elder (Acer negundo) and the big-leaf maple (Acer macrophyllum); and flutterers or spinners, such as those of the empress tree (Paulownia tomentosa) and the tree of heaven (Ailanthus altissima).

Taking inspiration from wind-dispersed seeds, John Rogers and colleagues design a series of fliers ranging in size from the microscale (below 1 mm) to the macroscale (above 1 mm). They use simulations and wind tunnel experiments to examine how aerodynamics are affected by changing design parameters such as the diameter, structure and wing type of the fliers. Rotational behaviours, as seen in helicopter and spinner seeds, enhance the stability and flying behaviour of these devices. Simple electronics can be integrated into the designs, with one example containing a circuit to detect airborne particles.

“These devices could form dynamic sensor networks for environmental monitoring, wireless communication nodes or various other technologies based on the network of Internet-connected devices called the Internet of Things”, writes E. Farrell Helbling in an accompanying News & Views. Helbling adds that further work is needed to understand how the fliers would behave in the wind and how other designs (parachuter- and glider-type fliers) might perform, but she suggests the current work paves the way for increased flier capabilities.