Materials with a temperature‐controlled reversible electrical transition between insulator and conductor are attracting huge attention due to their promising applications in many fields. However, most of them are intrinsically rigid and require complicated fabrication processes. Here, a highly stretchable (680% strain) liquid metal polymer composite as a reversible transitional insulator and conductor (TIC), which is accompanied with huge resistivity changes (more than 4 × 109 times) reversibly through a tuning temperature in a few seconds is introduced. When frozen, the insulated TIC becomes conductive and recovers after warming. Both the phase change of the liquid metal droplets and the rigidity change of the polymer contribute directly to transition between insulator and conductor. A simplified model is established to predict the expansion and connection of liquid metal droplets. Along with high stretchability, straightforward fabrication methods, rapid triggering time, large switching ratio, good repeatability, the TIC offers tremendous possibilities for numerous applications, like stretchable switches, semiconductors, temperature sensors, and resistive random‐access memory. Accordingly, a system that can display numbers and letters via converting alternative TIC temperature to a binary signal on a computer is conceived and demonstrated. The present discovery suggests a general strategy for fabricating and stimulating a stretchable transitional insulator and conductor based on liquid metal and allied polymers.

Flexible materials with the ability to be bent, strained, or twisted play a critical role in soft robots and stretchable electronics. Although tremendous efforts are focused on developing new stretchable materials with excellent stability, inevitable mechanical damage due to long term deformation is still an urgent problem to be tackled. Here, a magnetic healing method based on Fe‐doped liquid metal (Fe‐GaIn) conductive ink via a noncontact way is proposed. Further, multifunctional flexible electronics are designed with combined performances of superior remote self‐healing under magnetic field, water‐degradable, and thermal transfer printing, which attribute to three parts of the materials including Fe‐GaIn conductive ink, degradable PVA substrate, and adhesive fructose. The as‐made light emitting diodes (LED) circuit is demonstrated with both structural and functional repairing after single or multipoint damage. The self‐healing time from multipoint damage is pretty fast within 10 s. Due to the water‐soluble PVA film, the recycling process is simple via immersing into water. Through heating, the electric circuit on fructose can be transferred to other flexible substrate with high efficiency, which broadens the practical applications of the present system. The novel and multifunctional electronics hold great promise for self‐healing electronics, transient electronics, and soft robots.

silicon wafer, electronic skin, which is usually fabricated with mechanically compliant materials (low modulus, stretchable, and flexible) overcomes the fundamental mismatch between rigid devices and soft biological tissues. [13,14] At present, inorganic and organic electronic materials integrated with elastomeric substrates are the two popular approaches to fabricate electronic skin. Nonstretchable inorganic electronic materials, such as gold, copper, and silver, change the geometric structure to fit the stretched substrates. [15][16][17][18] It is obvious that the complicated, expensive fabrication methods, and limited stretchability of inorganic electronic materials restrict their widespread application. Alternatively, other inorganic electronic materials, such as nanoparticles [19][20][21] and carbon nanotubes, [22][23][24] are deposited on elastomer substrates to form a thin nanopath that can be extended when the substrates are stretched. With low-cost fabrication methods, such as direct printing [20,25] and transfer printing, [21] these materials have been highly successfully used to fabricate stretchable circuits, [26] sensing arrays, [27] and near field communication antennae. [21] Meanwhile, organic electronic materials, such as conductive small molecules and polymers and carbon-based conductive materials, [28] have good stretchability and their special chemical groups provide good conductivity. [29][30][31] However, the conductivities of nanoparticle layers and organic electronic materials are far lower than those of metal conductors. Thus, it is of great importance to develop new materials with both excellent conductivity and stretchability. Most electronic skin is fabricated on a flat device and subsequently transferred to skin. We suggest that the new conductive materials be directly printed onto the skin using a low-cost preparation method and be super-compliant and customizable.Liquid metal (eutectic gallium-indium, EGaIn) is an attractive conductive material that has shown significant promise for broad applications in flexible electronics. With its high electrical conductivity (EGaIn: 3.4 × 10 6 S m −1 ) [32] and excellent fluidity, [33] liquid metal has attracted great interest in many applications, such as stretchable antennae, [34,35] bioelectrodes, [36] strain sensors, [37] pressure sensors, [38] loudspeakers, [39] and soft robots. [40] Additionally, gallium is nontoxic with low vapor pressure, [41] which can be useful in an ambient environment. [42] Meanwhile, various patterning techniques of liquid metal have also been developed, such as microchannel injection, [43] atomized Because of its seamless skin interface, electronic skin has attracted increasing attention in the field of biomedical sensors and medical devices. Most electronic skins are based on organic or inorganic electronic materials. However, the low flexibility of inorganic materials and the limited conductivity of organic materials restricts their widespread use. A new approach is reported to fabricate electronic tattoos from N...

With inherent flexibility, high electroconductivity, excellent thermal conductivity, easy printability and biosafety, gallium-based functional liquid metals (LMs) have been increasingly evaluated for biomedical applications, especially as electronic skin (e-skin). Extending these versatile materials to more challenging applications is a worthwhile pursuit. To realize precise and spatiotemporal multisite tumor treatment under an alternating magnetic field (AMF), an oxidized GaIn (O-GaIn) mixture-based e-skin is developed and demonstrated to be printable. Compared with the commonly utilized nonoxidized GaIn, O-GaIn possesses outstanding adhesion to the skin surface and can be directly and quickly printed into various customized patterns.The LM e-skin thus constructed as conformable bioelectrodes on tumorbearing mice exhibits evident feasibility for administrating non-invasive wireless multisite tumor therapy under AMF exposure due to its favorable magnetothermal effects. These in vivo experiments reveal remarkable tumor growth inhibition and increased life span in mice, especially in the case of multilesion treatment. A favorable biomedical strategy based on O-GaIn material for developing future non-invasive and high-performance cancer therapy, which is also promising for treating whole-body diseases in the future, is provided.while O-GaIn displayed an uneven cut surface with air holes inside (Figure 1b-II,-III). In addition, SEM images revealed that GaIn had a glossy surface, while an obvious rough oxide layer appeared on the surface of O-GaIn-30 and many metal oxide particles arose on the surface of O-GaIn-60 (insets of Figure 1c-e). These SEM images illustrated that different stirring time

Shape tunable liquid metal nanoparticles were fabricated with characterization of biocompatibility, favorable photothermal conversion efficiency and tumor targeting capability for photothermal therapy.

Scheme 1. Schematic illustration of the LM/CA hydrogel preparation and endovascular embolization process. www.advancedsciencenews.com

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Electronic skin (e-skin) is attracting huge attention due to its promising applications in diverse fields, including biomimetic machines, artificial intelligence and smart robotics.