Fig. 2: Unidirectional flow behavior of liquid on BAS Mem.

A Optical images of time-dependent unidirectional flow behavior of liquid on BAS Mem. The droplet could unidirectionally spread. Scale bar = 3 mm. B High-speed digital images show that the liquid pinned within a single structure unit on BAS Mem, images representative of 3 experiments. Scale bar = 500 μm. C High-speed digital images show the spreading of liquid in a single structure unit on BAS Mem, images representative of 3 experiments. Scale bar = 500 μm. D Optical images show the flow behavior of liquid on different BAS Mems which were modified to display different surface contact angle. Scale bar = 3 mm.