Phoretic Liquid Metal Micro/Nanomotors as Intelligent Filler for Targeted Microwelding

Abstract

Micro/nanomotors (MNMs) have emerged as active micro/nanoplatforms that can move and perform functions at small scales. Much of their success, however, hinges on the use of functional properties of new materials. Liquid metals (LMs), due to their good electrical conductivity, biocompatibility, and flexibility, have attracted considerable attentions in the fields of flexible electronics, biomedicine, and soft robotics. The design and construction of LM‐based motors is therefore a research topic with tremendous prospects, however current approaches are mostly limited to macroscales. Here, the fabrication of an LM‐MNM (made of Galinstan, a gallium–indium–tin alloy) is reported and its potential application as an on‐demand, self‐targeting welding filler is demonstrated. These LM‐MNMs (as small as a few hundred nanometers) are half‐coated with a thin layer of platinum (Pt) and move in H2O2 via self‐electrophoresis. In addition, the LM‐MNMs roaming in a silver nanowire network can move along the nanowires and accumulate at the contact junctions where they become fluidic and achieve junction microwelding at room temperature by reacting with acid vapor. This work presents an intelligent and soft nanorobot capable of repairing circuits by welding at small scales, thus extending the pool of available self‐propelled MNMs and introducing new applications.

Trends in Micro‐/Nanorobotics: Materials Development, Actuation, Localization, and System Integration for Biomedical Applications

“…[ 194–196 ] For self‐propelled m‐bots, motility is commonly achieved from either the decomposition of a fuel by a catalyst or the degradation of the micro/nanorobots in the liquid environment. [ 194–199 ] From the literature regarding self‐propelled m‐bots, a considerable portion of the research focuses on the catalytic decomposition of hydrogen peroxide (H 2 O 2 ). [ 30,200–211 ] By integrating proper catalysts onto the m‐bots such as Au, Pt, and MnO 2 , H 2 O 2 can be decomposed to water and oxygen for gas propulsion.…”

Biomedical Micro‐/Nanomotors: From Overcoming Biological Barriers to In Vivo Imaging

“…[ 24–26 ] The other is powered by external field, such as magnetic field, [ 27–34 ] electric field, [ 35–38 ] ultrasonic field, [ 39–43 ] and light field. [ 44–46 ] Owing to the tiny size and unique mobility, MNMs have the potential as the next‐generation technology to provide novel solutions for environmental remediation, [ 47–50 ] sensing, [ 51–53 ] microwelding, [ 54 ] and biomedicine. [ 55–61 ] Especially in the field of biomedicine, MNMs are expected to shuttle through the human body in a noninvasive way to the diseased regions that are difficult to reach for traditional medical devices, and complete specific tasks such as targeted drug delivery and precise nanosurgery.…”

Leukocyte Membrane-Coated Liquid Metal Nanoswimmers for Actively Targeted Delivery and Synergistic Chemophotothermal Therapy

“…Liquid metal, a biofriendly material with excellent properties including low melting point, large surface tension, and high thermal and electric conductivity [ 32 – 34 ], has emerged for stretchable electronics and soft robots [ 35 – 39 ]. In our previous work [ 40 ], we demonstrated a first example of the soft rod-like liquid metal nanoswimmers which could transform from rod to droplet, fuse together, and be degraded in both an acidic buffer and biomedium of cancer cells.…”