Switchable capillary and drainage containers for programmable three-dimensional liquid manipulation

Abstract Capillarity-guided liquid manipulations are ubiquitous in nature. Multifarious bioinspired capillary microfluidic devices have been developed to control different liquid behaviors. However, current capillary systems still suffer substantial limitations in flexible three-dimensional (3D) liquid manipulation, especially in reversible liquid capture and release, programmable 3D liquid patterning, and large-scale multi-liquid manipulation. Here, we propose “switchable capillary and drainage containers” composed of connected frame units for versatile programmable 3D liquid manipulation. A small difference in the frame connections induces vastly distinct liquid behaviors, namely, liquid capture in capillary containers and liquid release in drainage containers. Liquid capture or release can be reversibly switched by establishing or breaking the liquid continuity between containers. Using predefined frame connections allows programmable 3D patterning of unary and binary liquids, enabling parallel multi-variable studies. The containers are proved to be powerful fluidic platforms with applications including reversible capillary sampling and release, high-flow evaporative humidifier, and efficient CO2 capture. We envision that the containers will open broad applications in materials science, interfacial chemistry, and biomedical research. Main text