Superhydrophobic\nMagnetic-Driven Reactor for Microliter\nDroplet Reaction Interface Visualization

The\ndevelopment of an efficient, convenient, and cost-effective\ndroplet-driven reactor to observe the reaction microphenomenon is\ncrucial for investigating the chemical reaction and synthesis mechanisms.\nHerein, an efficient and economical strategy by combining micro-extrusion\ncompression molding (μ-ECM) and surface modification was proposed\nto fabricate a superhydrophobic magnetic-driven reactor (SMDR) for\nmicroliter droplet reaction interface visualization. The wall-like\narray microstructures with favorable geometric uniformity and the\nnano-SiO<sub>2</sub> coating with uniform dispersion endow the SMDR\nwith robust superhydrophobicity, featuring a contact angle of 159.5\n± 1.0° and a rolling angle of 5.1 ± 0.5°. Due\nto the uniform dispersion of Fe<sub>3</sub>O<sub>4</sub> in thermoplastic\nelastomer (TPE), the SMDR possesses sensitive magnetic responsiveness,\nwhich can drive droplets to move rapidly, continuously, and losslessly\non horizontal and inclined planes, even on a plane with an inclination\nangle of up to 15°. Interestingly, the SMDR was successfully\nused to visualize the interface formation and evolution of three simple\nmixing/reaction processes, which provides a convenient, efficient,\nand low-cost method for the study of the droplet mixing reaction process\nand interface visualization.