An On‐Chip Liquid Metal Plug Generator

Abstract

Gallium‐based liquid metal nonspherical droplets (plugs) have seen increasing demand recently mainly because their high aspect ratios make them beneficial for a wide range of applications, including microelectromechanical systems (MEMS), microfluidics, sensor technology, radio‐frequency devices, actuators, and switches. However, reproducibility of the generation of such plugs, as well as precise control over their size, is yet challenging. In this work, a simple on‐chip liquid metal plug generator using a commercially available 3D microprinter is presented and the plug generator in poly(dimethylsiloxane) is replicated via soft lithography. Liquid metal plugs are generated via a combination of electrochemical oxidation, design of well‐defined constrictions based on Laplace pressure, and the application of modulated voltage control signals. It is shown that plugs of various aspect ratios can be generated reproducibly for channel widths of 0.5, 0.8, and 1.5 mm with constriction widths of 0.1 mm at 6 V. Laplace‐pressure‐controlled plugs in constricted channels are compared to modulated‐voltage‐generated plugs in straight channels showing that this technique provides significantly enhanced reproducibility and control over the size and spacing between the plugs. This work paves the way to sub‐millimeter liquid metal plugs generated directly on‐chip for on‐demand MEMS and microfluidic applications.

Liquid Metal-Doped Conductive Hydrogel for Construction of Multifunctional Sensors

“…Liquid metal (LM) has metallic and fluidic properties and has shown promising applications in soft and stretchable electronics, microfluidics, soft composites, catalysis, batteries, and biomedicines. − Numerous applications of LM have been explored, and interest in the utilization of the micro/nanodroplets of LM, which enabled particular properties related to flexibility, shape transformability, thermal properties, stimuli responsiveness, self-healing, and size-dependent behaviors, has been growing. − Embedding flexible LM into soft polymer matrices has enabled the creation of a variety of polymer–LM soft functional composites with a distinct combination of electrical, thermal, and mechanical properties. Compared with the traditional rigid conductive filler, the flexible LM can greatly improve the electrical conductivity of the hydrogel and reduce the internal stress caused by a mismatch in mechanical properties at the interface between the filler and hydrogel. , Nevertheless, it remains challenging to incorporate LM into water-confined polymer matrices to prepare conductive hydrogels with satisfactory mechanical properties.…”

Room‐Temperature Liquid Metals for Flexible Electronic Devices

“…As to configurable and microfluid devices, minimum wetting behavior and adhesive oxides should be put into effect to avoid excessive adhesion in those cannels and minimize their influences on the performance of the devices. [ 97–99 ]…”

Functional heterophasic liquid metals

“…Ga-based LM with excellent fluidity, negligible toxicity, and high electrical as well as thermal conductivity is receiving increasing attention in metal-polymer composites. [62][63][64] However, in most cases, the composites are not inherently conductive because they are not in intimate contact. The LM particles (LMPs) have to be sintered (e.g., mechanical, hightemperature, and laser sintering) to rupture the native oxide of LM to form a continuous percolating network in the polymeric matrix.…”

“…Ga‐based LM with excellent fluidity, negligible toxicity, and high electrical as well as thermal conductivity is receiving increasing attention in metal–polymer composites [62–64] . However, in most cases, the composites are not inherently conductive because they are not in intimate contact.…”