Fig. 2

Preparation process and characterization of surface morphology of the inverse opal substrates stretched at different directions. a Schemes of the fabrication procedures of the stretched inverse opal scaffolds (take the stretching angle of 0° as an example). b Schematic diagrams and c SEM images of the scaffolds stretched at different angles to the straight line of the single row of holes: (i) 0°, (ii) 15°, (iii) 30°, (iv) 45°. All these substrates were stretched 6 times of their initial lengths. Scale bars are 500 nm in (c)