Recoverable Liquid Metal Paste with Reversible Rheological Characteristic for Electronics Printing

Abstract

Gallium-based liquid metals are applied in the fabrication of soft electronics because of their conductivity and flexibility. However, the large surface tension and weak adhesion of liquid metals limit the available printing substrates. Recent researches indicate that amalgamating metal particles can turn liquid metal from fluid into a paste which has superb electrical conductivity, plasticity, and strong adhesion to substrates. In this work, a recoverable liquid metal paste was made by mixing eutectic Ga–In alloy and nonmetallic SiO2 (quartz) particles (Ga–In–SiO2 paste, called GIS). GIS has excellent conductivity and printable properties similar to those of previously reported liquid metal pastes. Furthermore, the bonding between Ga–In alloy and quartz particles is reversible. In acidic or alkaline solution, Ga–In alloy can be separated from quartz particles and agglomerated to bulk by stirring. Moreover, the study of the mechanism of adhesion behavior suggests that extruding fresh liquid metal droplets to form more oxide and shearing friction are the critical factors for adhesion. This work proposed a new liquid metal paste with a reversible rheological property and promoted the understanding of the working principle of liquid metal paste.

Polyphenol‐Induced Adhesive Liquid Metal Inks for Substrate‐Independent Direct Pen Writing

“…However, the development of efficient and accessible patterning methods of LMs onto different substrates is still challenging and requires a deeper understanding of the complex interfacial chemistry involved with LMs and their surroundings. [2,[10][11][12] Current strategies to pattern LMs onto substrates can be largely categorized as: 1) the use of LMs directly as inks for extrusion printing or writing, [13][14][15][16] and 2) the deposition of surface-stabilized LM dispersions (can be polymer or surfactant stabilized, or directly with native metal oxides) onto substrates where the mechanical sintering of the dispersed phase by an indenter or pressure bursting of the LM bubbles results in conductive traces in specific areas of the substrates. [17][18][19][20][21][22] These strategies are particularly suitable for microfluidic patterning or stencil writing with high metallic conductivity, [23] however while writing/ patterning onto substrates, they suffer from limited interactions with the substrate surfaces of variable chemistries, limiting their universal application.…”

Liquid Metal Direct Write and 3D Printing: A Review

“…Reproduced with permission. [75] Copyright 2020, ACS. c) Dispersing nickel particles into liquid metal via sonication forms a metal paste which can be extruded as continuous filament.…”

“…In this example, quartz powder mixed throughout a liquid metal results in the formation of a thick paste, which can be used to pattern liquid metal through a stencil. [75] Although stencil printing is not a direct-write technique, we mention this type of paste here as a method to modify the rheology of liquid metal, which may be useful for printing.…”

Interfacial Engineering of Room Temperature Liquid Metals

“…[127,128] Figure 9C displayed that silicate particle additives change the magnetic properties and adhesion properties of liquid metal droplets. [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.…”

“…[35][36][37] Moreover, it is widely studied and applied in thermal interface materials and microfluidics. [38,39] Interfacial effects of RTLMs also bring out as mentioned above significantly superior performances, which have found great potential applications in many fields, including advanced energy management, [39,40] flexible electronics, [32,34] microfluidics, [41] reconfigurable liquid metal antenna, [42] reversible liquid metal probe, [43] and biomedicine. [44][45][46][47][48] For the aforementioned scenarios, constructing a framework about the interfacial effects of RTLMs in whole various phases and corresponding interfacial reactions is in strong demand for further practices.…”