Morphable three-dimensional electronic mesofliers capable of on-demand unfolding

Development of miniaturized three-dimensional(3 D)fliers with integrated functional components has important implications to a diverse range of engineering areas.Among the various active and passive miniaturized 3 D fliers reported previously,a class of 3 D electronic fliers inspired by wind-dispersed seeds show promising potentials,owing to the lightweight and noiseless features,aside from the stable rotational fall associated with a low falling velocity.While on-demand shape-morphing capabilities are essential for those 3 D electronic fliers,the realization of such miniaturized systems remains very challenging,due to the lack of fast-response 3 D actuators that can be seamlessly integrated with 3 D electronic fliers.Here we develop a type of morphable3 D mesofliers with shape memory polymer(SMP)-based electrothermal actuators,capable of large degree of actuation deformations,with a fast response(e.g.,~1 s).Integration of functional components,including sensors,controllers,and chip batteries,enables development of intelligent 3 D mesoflier systems that can achieve the on-demand unfolding,triggered by the processing of real-time sensed information(e.g.,acceleration and humidity data).Such intelligent electronic mesofliers are capable of both the low-air-drag rising and the low-velocity falling,and thereby,can be used to measure the humidity fields in a wide 3 D space by simple hand throwing,according to our demonstrations.The developed electronic mesofliers can also be integrated with other types of physical/chemical sensors for uses in different application scenarios.

Probability-Based Analyses of the Snap-Through in Cage-Shaped Mesostructures Under Out-of-Plane Compressions

Three-dimensional(3D)mesostructures with distinct compressive deformation behaviors and tunable mechanical responses have gained increasing interest in recent years.3D cage-shaped mesostructures are representative framework structures widely exploited in 3D flexible electronics,owing to their unique cellular geometry and unusual mechanical responses.The snap-through behavior of cage-shaped mesostructures could potentially result in the performance degradation of electronics,while it could also be harnessed to design reconfigurable electronics.Due to the complicated deformation modes and random characteristics in experiments,the snap-through behavior of cage-shaped mesostructures remains largely unexplored,espe-cially in terms of probability-based analyses.In this work,we present a systematic study on the configuration evolution and snap-through of 3D cage-shaped mesostructures under out-of-plane compressions.Experimental and computational studies show the existence of two distinct deformation modes associated with the snap-through,which is controlled by the energy barrier based on the energetic analyses.Phase diagrams of the deformation modes decode how key geometric parameters and assembly strain affect the snap-through.Compressive experiments based on periodic arrays(10 × 10)of mesostructures provided a large amount of deformation data,allowing for statistical analyses of the snap-through behavior.These results provide new insights and useful guidelines for the design of 3D reconfigurable devices and multistable metamaterials based on 3D cage-shaped mesostructures.