Internally triggered motion of an object owns important potential in diverse application areas ranging from micromachines, actuator or sensor, to self‐assembly of superstructures. A new conceptual ...liquid metal machine style has been presented here: the transient state machine that can work as either a large size robot, partial running elements, or just divide spontaneously running swarm of tiny motors. According to need, the discrete droplet machines as quickly generated through injecting the stream of a large liquid metal machine can combine back again to the original one. Over the process, each tiny machine just keeps its running, colliding, bouncing, or adhesion states until finally assembling into a single machine. Unlike the commonly encountered rigid machines, such transient state system can be reversible in working shapes. Depending on their surface tension, the autonomously traveling droplet motors can experience bouncing and colliding before undergoing total coalescence, arrested coalescence, or total bounce. This finding would help mold unconventional robot in the sense of transient state machine that could automatically transform among different geometries such as a single or swarm, small or large size, assembling and interaction, etc. It refreshes people's basic understandings on machines, liquid metal materials, fluid mechanics, and micromotors.
A new conceptual liquid metal machine, the transient state machine, is demonstrated to work as either a single robot, separate moving elements, or spontaneously running motors swarm. The transient state can be reversible such that the discrete droplet machines injected from a source can combine back again to its original state. The colliding, bouncing, or adhesion phenomena involved are disclosed.
Stretchable Conductive CompositesIn article number 2200282, Thanh Nho Do and co‐workers developed a fabrication strategy to turn desired areas within non‐conductive elastomer composites into ...conductive ones via manipulation of magnetic liquid metal droplets. This fabrication strategy enabled the creation of composites that have high electrical conductivity, high stretchability, low modulus with one of the lowest filler ratios, and various configurations for a broad range of applications.
Room‐temperature liquid metals (RTLMs) have excellent shape reconfiguration capabilities, which make them ideal for flexible electrodes, sensors, and energy devices. However, due to the high surface ...tension and weak adhesion of RTLM, the types of printing substrates, patterning, and recovery processes are limited. It is essential to develop advanced encapsulation techniques for the patterning of RTLMs. Lignin has great potential for promotion as nanodispersants and nanocarriers because of its abundant hydroxyl groups and good self‐assembly properties. In this work, a green and facile encapsulation method using industrial lignin is reported for stable, uniform, and reproducible patterning of eutectic gallium–indium (EGaIn). Lignin‐encapsulated EGaIn particles exhibit good stability and can be patterned on the surface of various substrates with a simple ballpoint pen. The electrical resistance of the conductive tracks shows little change under bending and twisting (720°) conditions. More importantly, the lignin‐encapsulated system can be easily dissolved and regenerated, which is also supported by molecular dynamics simulations and density functional theory calculations. 96.9% of the EGaIn can be recovered from the system. These characteristics make it very environmentally friendly throughout the preparation process and find applications in flexible sensors, transient circuits, and many other areas.
A green and facile encapsulation method using industrial lignin is designed for stable, uniform, and reproducible patterning of eutectic gallium–indium (EGaIn). Lignin‐encapsulated EGaIn particles exhibit controllable sizes, good stability, dispersibility, adhesion, and extremely high recovery efficiency, making them very environmentally friendly during the entire process and finding applications in flexible sensors, transient circuits, and other areas.
The increasing demands for integration of renewable energy into the grid and urgently needed devices for peak shaving and power rating of the grid both call for low‐cost and large‐scale energy ...storage technologies. The use of secondary batteries is considered one of the most effective approaches to solving the intermittency of renewables and smoothing the power fluctuations of the grid. In these batteries, the states of the electrode highly affect the performance and manufacturing process of the battery, and therefore leverage the price of the battery. A battery with liquid metal electrodes is easy to scale up and has a low cost and long cycle life. In this progress report, the state‐of‐the‐art overview of liquid metal electrodes (LMEs) in batteries is reviewed, including the LMEs in liquid metal batteries (LMBs) and the liquid sodium electrode in sodium‐sulfur (Na–S) and ZEBRA (Na–NiCl2) batteries. Besides the LMEs, the development of electrolytes for LMEs and the challenge of using LMEs in the batteries, and the future prospects of using LMEs are also discussed.
Liquid metal electrodes (LMEs) endow batteries with long lifetimes and other merits for energy storage applications. The state‐of‐the‐art research progresses of LMEs in batteries are reviewed, including the LMEs for liquid metal batteries, sodium‐sulfur and ZEBRA batteries, as well as the development of electrolytes for LMEs and the challenges/future prospects of using LMEs in energy storage batteries.
Natural soft tissue achieves a rich variety of functionality through a hierarchy of molecular, microscale, and mesoscale structures and ordering. Inspired by such architectures, we introduce a soft, ...multifunctional composite capable of a unique combination of sensing, mechanically robust electronic connectivity, and active shape morphing. The material is composed of a compliant and deformable liquid crystal elastomer (LCE) matrix that can achieve macroscopic shape change through a liquid crystal phase transition. The matrix is dispersed with liquid metal (LM) microparticles that are used to tailor the thermal and electrical conductivity of the LCE without detrimentally altering its mechanical or shape-morphing properties. Demonstrations of this composite for sensing, actuation, circuitry, and soft robot locomotion suggest the potential for versatile, tissue-like multifunctionality.
Green Encapsulation
In article number 2310653, Lin Dai, Chuanling Si, and co‐workers present a green and facile lignin‐based encapsulation method for room‐temperature liquid metals with controllable ...sizes, good stability, dispersibility, adhesion, and extremely high recovery efficiency, that pioneer a promising application of lignin in high‐precision fields and promote transformation and upgrading of traditional lignin valorization.
As a class of emerging multifunctional soft materials, gallium‐based liquid metal (LM) amalgams, metal/nonmetal particles dispersed in an LM environment, suggest a combination of intriguing ...properties. In this article, Mg particles in gallium‐indium alloy for making new conceptual biomedical materials, which can adapt to any irregular skin surface, are introduced, and superior photothermal effect with a 61.5% photothermal conversion (PTC) increase with respect to that of the LM is realized. The formation of a new intermetallic phase Mg2Ga5 and adjustable surface roughness, which guarantees a rapid temperature increase when illuminated by laser, are found to be responsible for the photothermal effect enhancement. The obtained soft metallic mixtures also possess excellent thermal conductivity, favorable formability, together with benign biocompatibility. The potential use of the currently produced LM mixtures for conformable photothermal therapy (PTT) of skin tumors, which is hard to precisely heat otherwise via conventional ways, is explored. The soft Mg‐GaIn mixtures can adapt to irregular tumor shapes to achieve conformable and minimal invasive tumor treatment. In vivo experiments on skin‐tumor‐bearing mice show obvious tumor growth suppression and life span extension after PTT treatment. As a novel functional PTC material, the Mg‐GaIn mixtures exhibit promising potentials in the coming clinical cancer theranostics.
Soft, moldable, and highly conductive Mg‐doped EGaIn mixtures are fabricated for enhanced conformable photothermal conversion. The formation of intermetallic mixtures and the increase in surface roughness are found to be primarily responsible for the measured enhancement. In vivo precise skin tumor photothermal treatment using the Mg‐GaIn mixtures shows effective tumor ablation.
This paper describes a method to direct‐write 3D liquid metal microcomponents at room temperature. The thin oxide layer on the surface of the metal allows the formation of mechanically stable ...structures strong enough to stand against gravity and the large surface tension of the liquid. The method is capable of printing wires, arrays of spheres, arches, and interconnects.
Owing to their unique surface chemistry, room‐temperature pseudoliquidity, and high electrical conductivity, gallium‐based liquid metals (LMs) exhibit multifunctionality. To grant deformable and ...self‐flowing characteristics to LMs, magnetic particles are incorporated for precisely controlling the LM motion and shape deformability. However, LM surface‐adhesion and corrosivity hinders the integration of LMs into complex circuits and devices owing to potential alloying with other metals and contamination of their surroundings. In this study, a highly conductive Ti3C2Tx (MXene)‐encapsulated magnetic LM (MX–MLM) is developed using a feasible fabrication method. The MX–MLM comprises magnetic particles suspended within its core and self‐assembled MXene flakes on the surface to maintain the nonwettability and high electrical conductivity of a liquid droplet. The noncorrosivity and increased magnetism of the MX–MLM enable nonstick magnetic‐field‐induced locomotion and shape deformation on various surfaces including metals, oxides, and polymers. Furthermore, the MX–MLM exhibits recyclability and magnetic‐field‐induced self‐healing. To demonstrate its functionality, the MX–MLM is employed as a magnetointeractive, shape‐deformable, and locomotive top gate electrode in a transistor fabricated using a ferroelectric polymer gate insulator. The device exhibits excellent magnetointeractive synaptic capability for detecting and learning 3D path information.
An Ti3C2Tx (MXene)‐encapsulated magnetic liquid metal (MX–MLM) is synthesized for application to 3D‐motion‐adaptive synapses. The MX–MLM exhibits magnetic‐field‐induced shape deformability, locomotion, self‐healability, recyclability, and nonwettability and has excellent potential for application to single‐neural‐network artificial‐intelligence‐based magnetic‐path‐tracking systems to simultaneously sense, learn, and adapt to different magnetic fields.
PDF
