The researchers studied wind-dispersed seeds to help them design a microflier that falls at a slow velocity in a controlled manner. This behavior stabilizes the flight, ensures dispersal over a broad area and increases the amount of time it interacts with the air, making it suitable as a carrier for electronics to monitoring air pollution or airborne disease.
Most of the research was focused on the theoretical and practical optimization of the wing structure but examples were created that included an electronic payload that included sensors, a power source that can harvest ambient energy, memory storage and an antenna that can wirelessly transfer data to a smart phone, tablet or computer.
The research was reported in the September 23 issue of Nature.
Professor John Rogers led development of the device while Professor Yonggang Huang led the theoretical work.
"Evolution was likely the driving force for the sophisticated aerodynamic properties exhibited by many classes of seeds," said Professor Rogers, in statement. "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."
The researchers took inspiration from the tristellateia plant, a flowering vine with star-shaped seeds. To pinpoint the optimal structure, Huang led full-scale computational modeling of how the air flows around the device to mimic the tristellateia seed's slow, controlled rotation. Based on this modeling, Rogers’ group then built and tested structures in the laboratory.
Rogers said that the team has built its microfliers at sizes smaller than those found in nature. It has also been possible to make the 3D devices with precise wing angles from a 2D precursor. Attaching a rubber membrane the causes the wings to pop-up at the correct angles.
In the lab, Rogers’ group outfitted one device with all of these elements to detect particulates in the air. In another