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.

Microrotors are an indispensable component in micromachines, yet their usefulness has been limited by a lack of simple, inexpensive, and controlled fabrication technique that yields microrotors of controlled shapes in large quantities. To address this challenge, the chemical synthesis, characterization, and activation of tadpole-shaped catalytic microrotors that consist of a spherical, platinum (Pt)-coated head and a silver (Ag) nano-tail of tunable lengths are reported herein. Importantly, this tail spontaneously grows on Pt in an aqueous solution of Ag + and hydrogen peroxide (H 2 O 2), at a speed of ≈100 nm s −1 , preferably along the Ag (111) plane. The growth of Ag nanowires is attributed to an electrochemical reaction occurring on a tapered Pt cap, a mechanism corroborated by control experiments with photo-active titania microspheres, which introduce the additional advantage of light-controlled growth. The presence of a long Ag nano-tail on a tadpole-shaped microrotor breaks its symmetry and induces rotation in H 2 O 2 , and its structure-dependent dynamics is quantitatively studied and supported by numerical simulation. The chemical synthesis of microrotors with Ag nano-tails will introduce new designs of micromachines of controlled dynamics, as well as functional materials and devices where mild, controllable, and facile growth of Ag nanostructures is desired.

With the advanced development of miniaturized Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS) has extended its applications into the field of point-of-care testing (POCT) and demonstrated its great significance by virtue of its noninvasive property and capability of fingerprint identification. In the SERS-based analysis and/or sensing system, the preparation of a low-cost, high-performance SERS substrate is critically important. In this manuscript, vacuum filtration is utilized to fabricate the silver nanoparticles (AgNPs)-embedded nylon filter membrane (ANFM) as flexible paper-based SERS chips. By characterizing the typical analytes with a miniaturized smartphone-based Raman analyzer, the proposed SERS chips have successfully demonstrated good sensitivity, repeatability, and stability. The lowest concentration as detected can approach 1 pmol for rhodamine 6G (RH6G) and 10 pmol for both crystal violet (CV) and malachite green (MG), respectively. With the help of the microporous structure of the membrane, the ANFM-based SERS chips can implement the separation of small molecules from a complex mixture and can achieve “purified” SERS signals of targeted molecules. Besides, with the function of antifriction resistance and flexibility, the ANFM can serve as SERS papers to preconcentrate the contaminates by multiple swapping and further enhance the SERS signals for point-of-care analysis. Therefore, we demonstrate multifunctions of the flexible ANFM-based SERS chips, which provide a promising solution for the POCT analysis with the SERS technique on account of their flexibility and low fabrication cost.

Classic binary materials, ranging from polymer blends to table salts, contain equilibrium phases or crystals of two interacting components. Here, we report on the construction of binary colloidal materials out of equilibrium by employing active particles and passive particles that dynamically interact and organize. Key to our scheme is the introduction of photoactive microspheres whose activity can be precisely tuned. This allows us to leverage the complex nonequilibrium interplay between the constituent components for dynamic coassembly. A wide variety of binary structures have thus been realized, including the liquid–crystal phases and crystal–crystal phases via phase separation and, counterintuitively, the binary crystalline compounds. The obtained structures are validated by computer simulations, which reveal unexpected kinetic pathways that are unique for active systems. With these findings, our strategy could facilitate the design and fabrication of multicomponent materials beyond equilibrium.