Rapid meniscus-guided printing of stable semi-solid-state liquid metal microgranular-particle for soft electronics

Abstract

Liquid metal is being regarded as a promising material for soft electronics owing to its distinct combination of high electrical conductivity comparable to that of metals and exceptional deformability derived from its liquid state. However, the applicability of liquid metal is still limited due to the difficulty in simultaneously achieving its mechanical stability and initial conductivity. Furthermore, reliable and rapid patterning of stable liquid metal directly on various soft substrates at high-resolution remains a formidable challenge. In this work, meniscus-guided printing of ink containing polyelectrolyte-attached liquid metal microgranular-particle in an aqueous solvent to generate semi-solid-state liquid metal is presented. Liquid metal microgranular-particle printed in the evaporative regime is mechanically stable, initially conductive, and patternable down to 50 μm on various substrates. Demonstrations of the ultrastretchable (~500% strain) electrical circuit, customized e-skin, and zero-waste ECG sensor validate the simplicity, versatility, and reliability of this manufacturing strategy, enabling broad utility in the development of advanced soft electronics.

Looking into a crystal ball: printing and patterning self-assembled peptide nanostructures

“…Printing of liquid metal for soft electronic circuits was recently demonstrated using such a commercial bioprinter. 84…”

Surface-Embedded Liquid Metal Electrodes with Abrasion Resistance via Direct Magnetic Printing

“…A few efforts have been devoted to increasing the mechanical reliability of LM circuits by converting its liquid state into a biphasic (solid−liquid) state through heat treatment, 33,34 the use of pulsed laser lithography to obtain self-packaged structures, 35 or in situ deposition of adhesive LM particles by chemical modification. 36,37 thermally sensitive substrates, or the use of expensive equipment. Thus, it is highly needed to develop a simple and versatile way to create robust LM circuits for reliable use.…”

“…For the surface patterning, the liquid nature of LM conductors makes them prone to mechanical damage, requiring additional encapsulation steps to protect the delicate LM circuits. − Encapsulated LM cannot directly contact other objects and expose to the environment, limiting their practical use in many important application scenarios such as wearable and implantable electrophysiology monitoring, electrostimulation, and gas and temperature sensing. A few efforts have been devoted to increasing the mechanical reliability of LM circuits by converting its liquid state into a biphasic (solid–liquid) state through heat treatment, , the use of pulsed laser lithography to obtain self-packaged structures, or in situ deposition of adhesive LM particles by chemical modification. , However, these strategies have resulted in multistep operation for pretreatment and patterning of LM, being incompatible with thermally sensitive substrates, or the use of expensive equipment. Thus, it is highly needed to develop a simple and versatile way to create robust LM circuits for reliable use.…”

Conformally Adhesive, Large-Area, Solidlike, yet Transient Liquid Metal Thin Films and Patterns via Gelatin-Regulated Droplet Deposition and Sintering

“…Owing to the challenges encountered in the fabrication of LM-based stretchable conductors by direct deposition of bulk LMs on flexible substrates, deposition, and printing of LM micro- and nanodroplet inks are favorable since mechanical or laser-induced sintering of LM droplets can establish conductive paths on the substrates. − However, this strategy has several drawbacks, for instance, low conductivity, weak adhesion to substrates, requiring high accuracies of space and force for sintering, and it is only feasible for rather small areas. In some cases, surface modification of LM droplets can be employed to improve the adhesive properties of the LM pattern and even eliminate the mechanical sintering process. − …”