Recent Advancements in Liquid Metal Flexible Printed Electronics: Properties, Technologies, and Applications

Abstract

This article presents an overview on typical properties, technologies, and applications of liquid metal based flexible printed electronics. The core manufacturing material—room-temperature liquid metal, currently mainly represented by gallium and its alloys with the properties of excellent resistivity, enormous bendability, low adhesion, and large surface tension, was focused on in particular. In addition, a series of recently developed printing technologies spanning from personal electronic circuit printing (direct painting or writing, mechanical system printing, mask layer based printing, high-resolution nanoimprinting, etc.) to 3D room temperature liquid metal printing is comprehensively reviewed. Applications of these planar or three-dimensional printing technologies and the related liquid metal alloy inks in making flexible electronics, such as electronical components, health care sensors, and other functional devices were discussed. The significantly different adhesions of liquid metal inks on various substrates under different oxidation degrees, weakness of circuits, difficulty of fabricating high-accuracy devices, and low rate of good product—all of which are challenges faced by current liquid metal flexible printed electronics—are discussed. Prospects for liquid metal flexible printed electronics to develop ending user electronics and more extensive applications in the future are given.

Preparations, Characteristics and Applications of the Functional Liquid Metal Materials

“…After sintering, these nanoparticles could connect with each other (Figure 8c). [73][74][75][76][77][78][79][80][81][82][83][84][85] The functional liquid metals materials with low melting point could be encapsulated in soft materials to form soft conductors with high conductivity, high stretchability, and reconfigurability. [73][74][75][76][77][78][79][80][81][82][83][84][85] The functional liquid metals materials with low melting point could be encapsulated in soft materials to form soft conductors with high conductivity, high stretchability, and reconfigurability.…”

“…[72] Besides, other methods that aim at patterning the liquid metal on various substrates have also been developed, such as microfluidic channels injection, masked deposition, imprinting, microcontact printing, stamp lithography, direct writing, selective wetting, and so on. [73][74][75][76][77][78][79][80][81][82][83][84][85] The functional liquid metals materials with low melting point could be encapsulated in soft materials to form soft conductors with high conductivity, high stretchability, and reconfigurability. In order to enhance the stability of the connection between the liquid metal conductors and the soft materials such as PDMS, Wang et al put forward a novel liquid metal dual-trans (the liquid metal transfer printing and the freeze phase transition mechanism) printing strategy and fabricated flexible and functional circuits, as shown in Figure 8d.…”

Programmable Liquid Matter

“…As an alternative to Hg, the alloys of the low toxic and high conductive Gallium (Ga) -such as Galistan (an alloy of Ga,In,Sn) and EGaIn (alloy of Ga, In) -have attracted many researchers to investigate a variety of electrocapillary applications in optical switches [39], microfluidic circuits [29], flexible printed electronics [45] and 3D printing [39]. Crucially, a blob of one of these alloys, placed in an alkaline or acidic solution, would exhibit large transformations in surface tension when a voltage is applied, resulting in locomotion of the alloy.…”

Ultrauniform Embedded Liquid Metal in Sulfur Polymers for Recyclable, Conductive, and Self‐Healable Materials

“…[1][2][3][4] Liquid metals have been successfully applied in microfluidic chips, robotics, and stretchable electronics because of their unique advantages including high conductivity, fluidic nature, negligible toxicity, and flexibility. [1,2,[5][6][7][8][9][10][11][12][13][14] Although the properties of liquid metals have been extensively investigated, the broad applications of liquid metals are strictly hindered by several challenging issues. For example, liquid metals www.afm-journal.de www.advancedsciencenews.com (Supporting Information).…”