Optical maneuvering of dandelion-inspired fliers with vortex-enabled stability

Abstract

Maneuvering untethered, centimeter-scale airborne structures has been a long-standing challenge. Active flight systems, relying on high-power-density actuators alongside mechanical and electronic components, are constrained by critical limitations in energy delivery and miniaturization. In contrast, passive systems transported and distributed by the wind typically lack the capability for mid-air controlled maneuverability. Here, we report an ultralight (1.2 milligrams) hexagonal polymeric assembly capable of passive flight with optical control of its trajectory. This dandelion-inspired drone, dandidrone hereafter, incorporates six radially arranged filamentous structures, of which morphology is dynamically controlled through photomechanical deformation by six independent soft actuators made of liquid crystalline elastomer thin films. Compared to the diaspore of the dandelion, dandi drones demonstrate a similar terminal velocity (∼0.5 meters per second), 45% better positional stability and nearly zero rotational rate (1.68 ± 1.0° per second; natural seeds: 50.8 ± 17.7° per second). Particle image velocimetry and computational fluid dynamics simulation reveal that a stable asymmetric separated vortex ring underlies its flight stability, enabling mid-air steerability. When free-falling in a low-turbulent airstream, the light-driven hexapodal fliers demonstrate precise altitude control, reversible body flipping, pattern formation, interactive swarm, and controlled trajectories across the three-dimensional space. The results show that responsive materials with light-induced asymmetry can bring about maneuverability in air, paving the way for agile, untethered controlled microfliers.