Manipulation of Biomolecule-Modified Liquid-Metal Blobs

Semiliquid Metal Enabled Highly Conductive Wearable Electronics for Smart Fabrics

Wearable electronics incorporating electronic components into commonly used fabrics can serve as new-generation personalized health-care systems for applications ranging from health-care monitoring to disease treatment. Conventional rigid materials including gold, silver, and copper generally require a complicated fabrication process to be sewn into clothes. At the same time, other high-stretchable nonmetal materials such as conductive polymers generally have a limitation of low electroconductivity, restricting their further applications. Recently, gallium-based liquid metals have exhibited superior advantages in flexible electronics and have presented valuable potential in creative printing technologies. Here, we proposed a novel wearable electronics prepared through roller printing technology based on the adhesion difference of semiliquid metal (Cu-EGaIn, eutectic gallium-indium mixed with copper microparticles) on cotton fabrics and polyvinyl acetate (PVAC) glue. Results have shown that the surface topography and chemical interaction of fabrics and PVAC glue determine the adhesion effect with the Cu-EGaIn mixture. The electric experiments have demonstrated the electromechanical stability of the fabricated lines on fabrics. Further, a series of smart fabrics were developed including an interactive circuit, stretchable light-emitting diode array, and thermal management device with advantages of easy operation, low cost, and large-area fabrication to show practical applications in the method. This strategy may play an important role in the design and fabrication of smart fabrics, contributing to the development of customized health-care systems.

Coloration of Liquid-Metal Soft Robots: From Silver-White to Iridescent

Gallium-based room-temperature liquid metals are becoming increasingly attractive and outstanding candidates for designing soft robots because of their remarkable electrical conductivity, superior flexibility, excellent stability, and low toxicity. However, the color of liquid metals is limited to shiny silver-white with high reflectivity, which is not helpful for camouflage, like that found in natural soft animals such as cephalopods. Herein, a biomimetic chromatic liquid-metal soft robot with tunable structural colors is reported. Colors ranging from white to gold and black appear on the surface of liquid metal when placed on a graphite substrate and mixed with Al foil in an electrolyte solution. A stable liquid-metal functional material with a rainbow-like appearance is realized under the regulation of an electric field. Further composition and structure characterization reveals that it is a nanoscale Ga₂O₃ film that displays the multicolor characteristic. The nanostructural film indicates that light scattering of Ga₂O₃ occurs when the liquid metal is on the graphite surface, and thin-film interference triggers iridescence when the liquid metals are subjected to electrolysis, respectively. These results provide a route to create kaleidoscopic and colorful liquid metals, which are expected to have diverse applications, especially in reinforcing soft robot design with intelligent camouflage function.