Novel Membranes: Liquid‐based gating mechanism with tunable multiphase selectivity and antifouling behaviour

X. Hou, Y. Hu, A. Grinthal, M. Khan, J. Aizenberg
Wyss Institute - Harvard University,
United States

Keywords: filtration, membranes, phase separation, antifouling, liquid gating, energy efficient

Summary:

Living organisms make extensive use of micro and nanometer sized pores as gatekeepers for controlling the movement of fluids, vapors and solids between complex environments. The ability of such pores to coordinate multiphase transport, in a highly selective and subtly triggered fashion and without clogging, has inspired interest in synthetic gated pores for applications ranging from fluid processing to 3D printing and lab-on-chip systems. But although specific gating and transport behaviors have been realized by precisely tailoring pore surface chemistries and pore geometries, a single system capable of controlling complex, selective multiphase transport has remained a distant prospect, and fouling is nearly inevitable. Here we introduce a gating mechanism that uses a capillary stabilized liquid as a reversible, reconfigurable gate that fills and seals pores in the closed state, and creates a non-fouling, liquid-lined pore in the open state. Theoretical modeling and experiments demonstrate that for each transport substance, the gating threshold—the pressure needed to open the pores—can be rationally tuned over a wide pressure range. This enables us to realize in one system differential response profiles for a variety of liquids and gases, even letting liquids flow through the pore while preventing gas from escaping. These capabilities allow us to dynamically modulate gas–liquid sorting and to separate a three-phase air–water–oil mixture, with the liquid lining ensuring sustained antifouling behavior. Because the liquid gating strategy enables efficient long-term operation and can be applied to a variety of pore structures and membrane materials, and to micro as well as macroscale fluid systems, we expect it to prove useful in a wide range of applications. (Nature, 2015, doi:10.1038/nature14253)