Jiahui Xu,Yiling Dong,Jiang Yang,Ziyin Jiang,Longcheng Tang,Xiangrong Chen,Kun Cao
Dielectric elastomer actuators (DEAs) are widely used in robotics and artificial muscles because of their large energy densities and short response time. In this study, we developed two types of soft ray-inspired robots using solid–liquid interpenetrating silicone-based DEAs, named SIS DEAs. The optimized SIS DEA had an actuation strain of 79.8% at 20.43 kV/mm in a freestanding state, which was used as the muscle of the ray robot. To imitate the swimming behavior of the ray, the effect of the driving frequency on the velocity of the ray robot was explored. The ray robot achieved a maximum swimming rate of 5.7 mm/s when the driving frequency was ∼0.6 Hz. In addition, the steady-state and the transient simulation were carried out to reveal the mechanism of the ray robot's electro-swimming. The results revealed that the actuating deformation of the SIS DEAs caused the electro-deformation of the ray robot, and the periodical electro-deformation generated the high-speed vortex beneath the robot to push the ray robot forward. The high actuation strain in the freestanding state and the shape customizability of the SIS DEAs made it an ideal alternative to muscles for various soft robots.
Swarming micro/nanomotors can self-organize into cohesive groups to execute cooperative tasks. To date, research work has focused on the construction of egalitarian microswarms composed of similar individuals. The construction and collective behaviors of hierarchical leader–follower-like microswarms are demonstrated. By inducing converging electrohydrodynamic flows under an AC electric field, dielectric microparticles with different sizes and dielectric properties can hierarchically self-organize into leader–follower-like microswarms under attractive electrohydrodynamic interactions, and show novel emergent collective behaviors. First, different from immobile single constituents or egalitarian clusters, the hierarchical microswarms autonomously move with tunable speed. Second, they exhibit multimode collective photoresponses emerging from different behaviors of the constituents in response to light signals. With a vertical UV signal, the photoresponsive followers tend to surround the leader and stop the microswarm. In response to sidewise UV signals, the constituents with stronger phototaxis would migrate to the position away from light stimuli, and thus the microswarms reorient parallel/antiparallel to the light direction and perform collective positive/negative phototaxis. Due to differential roles and huge design spaces of constituents, the hierarchical microswarms are envisioned to possess merits of high-efficiency, multiresponsiveness, and multifunctions, and may serve as intelligent micro/nanorobot systems for biomedicine and microengineering.