Lightweight Liquid Metal Entity

Abstract

Liquid metals are of great importance in developing wearable devices and soft robotics owing to its high conductivity and flexibility. However, the high density of such metals turned out to be big concern for many practical situations. With generalized purpose, a new conceptual material as lightweight liquid metal entity, which can be as light as water, is proposed here. For illustration, an unconventionally ultralight material composed of eutectic galliumindium alloys (eGaIn) and glass bubbles is demonstrated, whose density can be reduced below 2.010 even 0.448 g cm‐3, even lighter than water, but still maintains excellent conformability, electric conductivity, and stiffness variety under temperature regulation. Such material is further adopted to build various complicated structures through origami or force regulation, representing various application scenarios and can be reused for eight times without evident loss in function. Based on these tests, buoyancy component for water‐related devices is designed, which offers the functions of a switch and loading element. The lightweight liquid metal entities are promising for making diverse advanced soft robotics and underwater devices in the near future.

Interfacial Engineering of Room Temperature Liquid Metals

“…[34] Moreover, taking advantage of the favorable wettability between liquid metal and glass, a much lower density of liquid metal composite was realized by adding hollow glass beads ( Figure 9D). [24] The adhesion of polymers and the chelation of cations in liquid metal droplets with macromolecules can also realize the stable dispersion of liquid metal composites in nanoscale. Zhou et al [133] coated nano-liquid metal droplets with polydopamine (PDA) to achieve photothermal conversion.…”

“…[ 34 ] Moreover, taking advantage of the favorable wettability between liquid metal and glass, a much lower density of liquid metal composite was realized by adding hollow glass beads (Figure 9D). [ 24 ]…”

“…Reproduced with permission. [ 24 ] Copyright 2020, Wiley‐VCH. E) Self‐capsulation liquid metal into thermal/photomoldable powders.…”

“…The surface is a type of interface, which specifically refers to the gas phase substance in interfacial behavior. In the processes of thermodynamics, [ 16,17 ] surface absorption, [ 18,19 ] controllable wetting, [ 6,13,20 ] material catalysis, [ 21,22 ] redox, and other physical and chemical reactions, [ 23,24 ] RTLMs inevitably contact with other substances with different phase states. Even the pure liquid metal would contact with oxygen in the air to yield a thin protective film.…”

Liquid Metal Based Flexible and Implantable Biosensors

“…Higher dynamic viscosity, higher adhesion, and lower surface tension can be obtained while conductivity remains mostly consistent [ 35 ]. As a result, liquid metal can be easily molded into various shapes ( Figure 1 d) [ 36 ], and could be used to make sensor elements and sensor circuits [ 37 ]. In addition, many metal particles (Fe, Cu, and Ni) and liquid metal may form an intermetallic compound [ 28 , 38 , 39 ].…”