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

Abstract

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.

Interfacial Engineering of Room Temperature Liquid Metals

“…© 2021 Wiley-VCH GmbH instead of the traditional silver color. [31] Figure 7A showed the color change from silver-white to gold of the surface of the liquid metal and finally to darkness color changes when placed on a graphite substrate and mixed with aluminum foil in an electrolyte solution. Under the adjustment of the electric field, the upper and lower surfaces of the film are smooth, and the incident light interferes with the film so that the liquid metal surface can appear a rainbow-like distribution.…”

“…Room temperature liquid metals (RTLMs) composed of gallium-based alloys are emerging as crucial functional materials with various unique properties, and have attracted extensive attention over academia, industry, and more areas. Normally, gallium-based liquid metals presented the thin surface oxides with a thickness of ≈1-3 nm, which were effectively passivated fantastic phenomena of RTLMs in electrolytes, [29][30][31] as well as the applications of printed electronics and soft machines on solid substrates. [32][33][34] The surface structure of RTLMs possessing fantastic characteristics of self-limiting and inherent smoothness warrants further investigation in the surface catalysis.…”

SILVER SULFATE (Ag2SO4): MOLECULAR ANALYSIS AND ION TRANSPORT

“…Massa molar (136)(137)(138)(139) 311,7990 g/mol Penampilan (140)(141)(142) Kristal tidak bewarna Bau (143)(144)(145) Tidak Berbau…”

A Versatile Approach for Direct Patterning of Liquid Metal Using Magnetic Field

“…Liquid metals (LMs) of gallium (Ga)–based alloys have attracted much attention due to their excellent properties such as nontoxicity, high electric/thermal conductivity, deformability, self‐healing ability, and unique surface chemistry . These properties have led to many promising applications in flexible electronics, soft matter, robotics, optics, microfluidics, green synthesis, and wearable sensing . One integral and crucial step toward most of these applications is to pattern the LM on different substrates to construct functional components and devices.…”