Fig. 1: Technological route of preparation mimicking meridian system of nature frond leaves.

a Photograph of nature plant leaves with special meridians. b Digital images of different prepared nanofibrous membrane. c TTPCN membrane with thickness of 0.7 mm shows special grid-like morphology and multi-level structure, both the scale bars in c (II) and c (V) are 500 μm. d TTPCN membrane shows good flexibility. e Typical fabrication process of TPPCN membrane.