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.