Bio‐Inspired Differential Capillary Migration of Aqueous Liquid Metal Ink for Rapid Fabrication of High‐Precision Monolayer and Multilayer Circuits

Abstract

Manipulating liquid metal inks to create conductive microstructures has attracted widespread interest as liquid metal microstructures are turning into influential components in flexible electronics. However, it is challenging to prevent the issues with low precision, low efficiency, and residue caused by sedimentation, free diffusion, and the Marangoni effect. Inspired by the water transport in plants, the wetting-induced assembly method based on the differential capillary effect for liquid metal ink is created to realize the facile and rapid manufacture of liquid metal conductive microstructures. The single-micron accuracy circuits with a minimum of ≈4 µm straight lines are fabricated to a centimeter scale. This method can also be extended to the preparation of multilayer circuits (minimum 5 µm through hole). The resulting entirely flexible stretchable circuits make it possible to construct highly stretchable devices, such as flexible transparent conductors and stretching sensors. Transparent conductors exhibit excellent mechanical (maximum ≈750% tensile rupture limit) and optoelectronic properties (the transmittance reaches ≈87% and the sheet resistance is ≈0.5 Ω/□)|making them suitable for optically-clear electromagnetic shielding. This study offers a fresh and plain approach to solving the assembly problem of liquid metal inks, paving the way for the creation of flexible electronic devices

Self-Adhesive, Biocompatible, Wearable Microfluidics with Erasable Liquid Metal Plasmonic Hotspots for Glucose Detection in Sweat

“…We used liquid gallium as ink for writing. In the actual writing process, the line width is determined by many parameters, such as writing speed, needle inner diameter, distance between the needle tip and writing plane, writing substrate material, and air pressure applied to the syringe. − In our work, we set the writing speed to 1 mm/s, the distance between the needle tip and the writing plane to 200 μm, the air pressure into the syringe to 0.02 MPa, and the writing substrate material to PEIE-PDMS-40. Figure b shows Ga wires with different line widths (60 μm-1500 μm) written by needles with different inner diameters.…”

Liquid Metal–Polymer Conductor-Based Conformal Cyborg Devices

“…It can be patterned by screen-printing, which has a low cost and can be fabricated on a large scale (Figure a), the main restriction of this method is the resolution (50 μm). The LMNPs can be patterned by filling them into the microfluidic channel (Figure a), this method can realize a high resolution (5 μm), and the filling efficiency is the main disadvantage. Researchers find that this process can accelerated by differential capillary migration of aqueous LM ink .…”

“…The LMNPs can be patterned by filling them into the microfluidic channel (Figure a), this method can realize a high resolution (5 μm), and the filling efficiency is the main disadvantage. Researchers find that this process can accelerated by differential capillary migration of aqueous LM ink . By using a stencil and a sprayer, the LMNPs can be patterned on different surface morphology (Figure b).…”

Passivation-Free, Liquid-Metal-Based Electrosynthesis of Aluminum Metal–Organic Frameworks Mediated by Light Metal Activation

“…Liquid metals are a genre of metals with low melting points, which are commonly referred to the family of post transition metals, e.g., gallium (Ga), indium (In), and bismuth (Bi). − Unlike conventional solid metals, liquid metals, especially Ga, can remain in the liquid state at close to room temperature and can be utilized for alloying other metals into liquid-state mixtures. − The electron-rich interface and liquid state of liquid metals endow great potential for facilitating chemical reactions and can be applied for the synthesis of miscellaneous functional materials. ,− …”