Advances in the Development of Liquid Metal-Based Printed Electronic Inks

Abstract

As a newly emerging additive manufacturing technology, printed electronics based on the printing principle has received more and more attention. Compared to conventional electronics manufacturing, such technique has many advantages such as speediness, flexibility, personalized customization, and low cost. Currently, there are three kinds of typical conductive inks used in printed electronics-conductive carbon ink, conductive polymer, and metal conductive ink. However, the electrical conductivities of the conductive carbon ink and the conductive polymer are typically lower than 10 5 S/m, which impedes their application in high-sensitivity circuit fabrication. As to the metal conductive ink, post-treatments via long time curing process are often needed, which reduce the printing speed and improve the manufacturing costs. As an alternative, liquid metal is emerging as a new class of conductive ink and is thus becoming an important research focus. Such material has unique merits such as high electrical conductivity, simple preparation process, requesting no post-processing after printing, and so on. To further push forward the research on liquid metal-based printed electronics, this article strives to present an overview on the related research advancement in recent years. Properties of liquid metal such as oxidation, wettability, and conductivity are discussed. Liquid metal techniques including tapping mode electronic printing, atomized spray printing, microcontact printing, laser sintering method of liquid metal nanoparticles, transfer printing, masked deposition, liquid metal corrosion sculpture method, colorful liquid metal circuit fabrication method, and hybrid rolling and transfer printing method are systematically expounded. Prospective direction worth pursuing is outlined.

Electrochemically Enabled Embedded Three-Dimensional Printing of Freestanding Gallium Wire-like Structures

“…Gallium, a metal with the melting point at around 29.8 °C, recently has attracted extensive attentions from researchers especially in the field of flexible electronics and wearable devices. , Apart from the desirable properties such as high electrical conductivity and good ductility that share with other flexible conductive materials, the transformable mechanical property of gallium can enable the reversible transition between the rigid static state and the flexible reconfigurable state of devices, which can accommodate versatile systems for more diverse applications. − As many electronic devices, such as inductors, capacitance, and antennas, work more efficiently in 3D forms, the 3D printing of freestanding gallium structures in an ambient environment present a great value especially in the applications such as wearable electronics and biomedical devices.…”

Advances in Liquid Metal-Enabled Flexible and Wearable Sensors

“…Based on the fluidity of liquid metal, the concept of liquid-metal printed electronics was proposed [79,80]. Researches have proven that liquid metal can be used as ink and printed directly by a brush or a roller ball pen [81][82][83]. Compared to a traditional printed circuit board, this made electronics fabrication more convenient and rapid.…”

Liquid Metal-Based Devices: Material Properties, Fabrication and Functionalities

“…For metal conductive inks, a long-term curing process is required for post processing, which reduces the printing speed and increases the manufacturing cost. As an alternative, the LM conductive ink is becoming an important research focus [33].…”