Fig. 4: Microchannel structures fabricated by soft demoulding.

a The thinnest channel (10 µm in diameter) fabricated in this work. Scale bar, 50 µm. b, c The microchannel and its circular cross-section. Scale bars, 50 µm. d The microchannel with tapered geometry. The diameter of the left side of the tapered channel is 250 µm, and the right-side diameter is 40 µm. Scale bar, 200 µm. e The microchannel with a spindle-knotted shape. Scale bar, 500 µm. f The microchannel lattice. Scale bar, 500 µm. g The helical microchannel. Scale bar, 200 µm. h The branched microchannel. Scale bar, 100 µm. i The microchannel with plectoneme structure. Scale bar, 500 µm. j, k are the feature parts of f and i, respectively. Scale bars, 200 µm. l–q The novel 3D microchannel structures. Both n and o show different views of the same prototype and the same to p and q. Scale bars, 5 mm. Images in a–q are representative of five independent microchannels (experimental replicates). r Feature size and geometric flexibility for microchannel fabrication studies (Assembly capability is not considered for comparison).