Programmable unidirectional liquid transport on peristome-mimetic surfaces under liquid environments

Programmable liquid unidirectional transport is important in fluidic applications, such as microfluidics, oil-water separation, and self-lubrication. Despite commendable progress, previous research mainly focused on the unidirectional transport of liquids in an air environment. In multi-fluid systems, the unidirectional transport of one liquid under another immiscible liquid phase, even though urgently needed, still remains a challenge. To solve this cutting-edge problem, we mimicked the peristome of Nepenthes alata and 3D printed peristome-mimetic surfaces to achieve rapid, long-range and unidirectional liquid transport under another immiscible liquid phase. Significantly, we achieved unidirectional transport in a one-dimensional linear trajectory, a two-dimensional curve, and even in a three-dimensional infinite space. Our strategy offers opportunities for liquid transport and micropatterns in liquid environments for various applications.