Ultrafast Growth and Locomotion of Dandelion-Like Microswarms with Tubular Micromotors.

Abstract

Dynamic assembly and cooperation represent future frontiers for next generations of advanced micro/nano robots, but the required local interaction and communication cannot be directly translated from macroscale robots through the minimization because of tremendous technological challenges. Here, an ultrafast growth and locomotion methodology is presented for dandelion-like microswarms assembled from catalytic tubular micromotors. With ultrasound oscillation of self-generated bubbles, such microswarms could overcome the tremendous and chaotic drag force from extensive and disordered bubble generation in single units. Tubular MnO2 micromotor individuals headed by self-generated oxygen bubbles are ultrasonically driven to swim rapidly in surfactant-free H2 O2 solutions. A large bubble core fused from multiple microbubbles is excited to oscillate and the resultant local intensified acoustic field attracts the individual micromotors to school around it, leading to a simultaneous growth of dandelion-like microswarms. The bubble-carried micromotor groups driven by ultrasound could swarm at a zigzag pattern with an average speed of up to 50 mm s-1 , which is validated in low H2 O2 concentrations. Additionally, such superfast locomotion could be ultrasonically modulated on demand. The ultrafast microswarm growth and locomotion strategy offers a new paradigm for constructing distinct dynamic assemblies and rapid transmission of artificial microrobots, paving the way to a myriad of promising applications.