Exploiting the interfacial instability of liquid-infused Janus membranes for versatile liquid gating

Hypothesis With varied affinities for distinct liquids, liquid/solid interfaces can exhibit different stability against external liquids. For liquid-infused Janus membranes with different surface chemistry, there may be significant osmotic pressure gradients across the membrane, facilitating liquid gating of various liquids in diverse systems. Such strategy may highly widen the application areas of liquid gating technology. Experiments Liquid-infused Janus membranes were prepared via the combination of hydroxyapatite (amphiphilic but more water-loving) on one side and 3-(dodecylamino) propane-1-sulfonic acid (amphiphilic but more oil-loving) on the other side and subsequent infusion of various liquids (water or oils). The gating property of them was studied for all the conditions and the application potential in various areas including medical and micro-reaction was also explored. Findings After being infused with certain liquids (i.e., water or oils), the obtained membranes displaying opposite affinity toward water and oils can universally gate immiscible liquids at a high rectification ratio in air and in liquids. The interfacial instability of liquid films on the reverse sides was found to be critical in the achievement of liquid gating. Moreover, such gating property is also applicable in the transportation of various soluble substances (ions and drugs) and facilitating the dislodgement of blood.