Superhydrophobic Magnetic-Driven Reactor for Microliter Droplet Reaction Interface Visualization

The development of an efficient, convenient, and cost-effective droplet-driven reactor to observe the reaction microphenomenon is crucial for investigating the chemical reaction and synthesis mechanisms. Herein, an efficient and economical strategy by combining micro-extrusion compression molding (μ-ECM) and surface modification was proposed to fabricate a superhydrophobic magnetic-driven reactor (SMDR) for microliter droplet reaction interface visualization. The wall-like array microstructures with favorable geometric uniformity and the nano-SiO₂ coating with uniform dispersion endow the SMDR with robust superhydrophobicity, featuring a contact angle of 159.5 ± 1.0° and a rolling angle of 5.1 ± 0.5°. Due to the uniform dispersion of Fe₃O₄ in thermoplastic elastomer (TPE), the SMDR possesses sensitive magnetic responsiveness, which can drive droplets to move rapidly, continuously, and losslessly on horizontal and inclined planes, even on a plane with an inclination angle of up to 15°. Interestingly, the SMDR was successfully used to visualize the interface formation and evolution of three simple mixing/reaction processes, which provides a convenient, efficient, and low-cost method for the study of the droplet mixing reaction process and interface visualization.