Ultrafast Growth and Locomotion of Dandelion‐Like Microswarms with Tubular Micromotors

Abstract

Microrobots that could perform precise manipulations in micro/nano scales have attracted a tremendous recent attention towards past decades for helping human beings to explore 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 MnO 2 micromotor individuals headed by selfgenerated oxygen bubbles are ultrasonically driven to swim rapidly in surfactantfree H 2 O 2 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 H 2 O 2 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. the unknown nanoworld. [1] With intensive efforts devoted from multidisciplinary fields, diverse propulsion mechanisms for microrobots have been unlocked to develop numerous microrobot platforms activated by internal chemical reactions or external physical fields (magnetic, acoustic, optic, electrostatic, or thermo, etc.). [2] In addition, versatile utilizations have demonstrated that single or few number of functionalized microrobots could efficiently undertake fantastic missions in a precise and active manner, such as targeted cargo delivery, nanosurgery, and molecular imaging, etc. [3] However, their limited capacity for payloads embedment and poor motility in harsh environment (e.g., strong ambient flow, high ionic environment, etc.) have significantly hindered such promising platform from the proof-of-concept research to practical applications. Inspired by the global collective behaviors of living creature groups in nature, [4] such as shoaling fish and flocking birds, self-organized aggregation, or swarming of micromotor groups have been coming under the spotlight. These group behaviors could realize the reinforced mobility, load capacity, and robustness that individual ones cannot offer, thereby illuminating more prospects in fulfilling complex tasks. [5] Among several representative geometries of micromotors, tubular micromotors have arou...

Cubic nano-silver-decorated manganese dioxide micromotors: enhanced propulsion and antibacterial performance

“…Because of the free-swimming strategy, the control of the motion direction is not essential here; however, it could be regulated by a magnetic field after incorporating the magnetic coating for further target capture, delivery, and killing. 10,40,41 The association of ultrasound with chemically-driven micromotors will give distinct motility, such as group assembly and ultrafast zigzag motion, 42 therefore, leading to concentrated liberated ions in localized regions and a rapid mass transfer. Typically, these bubble-propelled micromotors could result in a violent mixture in the localized-region and ought to accelerate the mass transfer.…”

Manganese‐Based Micro/Nanomotors: Synthesis, Motion, and Applications

“…[70] A number of tubular Mn-micro/nanomotors are able to construct a group schooling on the bigger oscillated bubbles, which are formed at the bottom opening of an individual Mn-micro/nanomotor. [71] The intelligent collective motion opens a new gate to condense more functionalized Mn-micro/nanomotors in a small region, promoting the efficiency of functionalization (e.g., removing contaminants and killing cancer cells).…”

Investigating Time‐Dependent Active Motion of Janus Micromotors using Dynamic Light Scattering

“…[ 1–8 ] The characteristic self‐propulsion exhibited by micromotors enables their use in a variety of applications, such as drug delivery, [ 9–16 ] environmental clean‐up, [ 17–21 ] or self‐assembly of active ensembles. [ 22–28 ] Most commonly, self‐propelling micromotors exhibit a two‐sided Janus morphology, thus termed a Janus micromotor (JM). One face of the JM is typically inert, while the other face is either catalytic, producing local anisotropic chemical gradients, [ 29–34 ] or interacts with an external field (such as light [ 19,21,35–38 ] or magnetic fields [ 32,39 ] ).…”