Collective Motion of Magnetic Soft Cilia Controls Droplets and Nanozyme Catalysis

Abstract

Bioinspired magnetic cilia attract the tremendous attention of researchers due to flexible nature and remotely controlled manipulations of droplets and fluids. Nonetheless, controlling catalytic process by magnetic cilia remains underexplored. Here, we present magnetic soft cilia carpets with different magnetizations to control enzyme-like chemical reactions. We demonstrate a methodology to optimize material, geometric, and magnetic field parameters to achieve high-frequency oscillations of the cilia under an alternating magnetic field at 15 Hz. We also show stable oscillation of water-based droplets on the cilia surface at a magnetic field frequency of 10 Hz without droplet detachment. Furthermore, we demonstrate enhanced droplet catalysis resulting from droplet oscillation on the cilia surface. As a concept for automated lab analysis, we demonstrate droplet transport by magnetic cilia onto a flexible pH sensor. Finally, as a proof-of-concept, we show control of nanozyme reaction rates by varying cilia magnetization angles, achieving a fourfold enhancement of reaction rate under a rotating magnetic field compared to unmagnetized cilia. These findings offer a promising approach to remotely control enzyme-like reactions and droplet catalysis using magnetic cilia.