Dandelion-Inspired, Wind-Dispersed Polymer-Assembly Controlled by Light.

ABSTRACT

The rise of stimuli-responsive polymers has brought about a wealth of materials for small-scale, wirelessly controlled soft-bodied robots. Thinking beyond conventional robotic mobilities already demonstrated in synthetic systems, such as walking, swimming and jumping, flying in air by dispersal, gliding, or even hovering is a frontier yet to be explored by responsive materials. The demanding requirements for actuator's performance, lightweight, and effective aerodynamic design underlie the grand challenges. Here, a soft matter-based porous structure capable of wind-assisted dispersal and lift-off/landing action under the control of a light beam is reported. The design is inspired by the seed of dandelion, resembling several biomimetic features, i.e., high porosity, lightweight, and separated vortex ring generation under a steady wind flow. Superior to its natural counterparts, this artificial seed is equipped with a soft actuator made of light-responsive liquid crystalline elastomer, which induces reversible opening/closing actions of the bristles upon visible light excitation. This shape-morphing enables manual tuning of terminal velocity, drag coefficient, and wind threshold for dispersal. Optically controlled wind-assisted lift-off and landing actions, and a light-induced local accumulation in descending structures are demonstrated. The results offer novel approaches for wirelessly controlled, miniatured devices that can passively navigate over a large aerial space.