Magnetically controlled super-wetting surface switching between ultra-low and ultra-high droplet adhesion

Abstract

Controlled liquid adhesion behaviors on super-wetting surfaces have gained significant attention, however, precise controlling of adhesion behavior is extremely hard to realize due to some inherent limitation in surface chemistry or morphology. Herein, we report a silicone-oil-infused magnetic porous polydimethylsiloxane (SMPP) surface with magnetically tunable super-wetting behaviors. Benefiting from the magnetic-field-responsive structure and interconnected porous characteristics, the SMPP can use magnetic field to control the seepage and absorption of silicone oil in the micropore channels, thereby precisely changing the adhesion of the water droplets on the surface. Compared to conventional super-wetting surfaces, this SMPP surface displays reversible in-situ conversion from ultra-high to ultra-low droplet adhesion with sliding angles ranging from 3° to 180° that hold up well even after severe cutting or abrasion. We also demonstrated that this tunable adhesion behavior can be used not only to enhance droplet manipulation in spatiotemporal but also to design unique microfluidic microreactors and antigravity transport devices. We envision that this proof-in-concept surface can serve as an important component of integrated control systems for intelligent manipulators, biochemical reactions, fluid transport, and biomedical analysis.