Amalgamation‐Assisted Control of Profile of Liquid Metal for the Fabrication of Microfluidic Mixer and Wearable Pressure Sensor

The presence of microdomes can significantly increase the surface roughness, contact area, and deformability of materials, which have been adopted in many fields including microfluidics, wearable devices, and microanalysis systems. However, the shape of liquid metal (LM) droplet is defined by the density and surface energy, which has very limited room to tune. In this work, a simple, low-cost method to effectively control the profile of LM using the masked amalgamation is presented. The LM amalgamates the masked copper surface to create the complex microdomes with various aspect ratios, sizes, profiles, and structures. The concave dome replicated from the LM mold has been demonstrated to enhance the microfluidic mixing performance. With a pattern transfer technique, the microconvex domes can be patterned on the surface of stretchable conductive composites to develop a flexible and sensitive pressure sensor. This sensor exhibits a fast response time, a wide working range, and an enhanced sensitivity for detecting small strains. As such, the fabricated microdomes exhibit a great potential to enable the fabrication of high-performance sensors, microfluidic platforms, and micro total analysis systems.