Fig. 1. Preparation procedure of fingerprints.

Fig. 2. Fingerprints with hierarchical helix structures. (a) Polarized optical microscope textures of unidirectionally aligned fingerprints; scale bar, 50 µm; (b)–(d) schematics of the hierarchical helical structure, planar helices with helical axes perpendicular to substrates, and the self-adapted distorted helical structure near the air–film interface; the distance between two adjacent layers equals half a pitch.

Fig. 3. Photopatterned hierarchical fingerprints. (a) Binary periodic alignment and periodic zigzag fingerprint pattern; (b) continuous periodic alignment and C-shaped fingerprint superstructure; scale bar, 50 µm.

Fig. 4. Dual photopatterning of rotational fingerprints. (a) Changing process from a radiating structure to Archimedean spiral during the uniform UV light exposure; (b) changing process from an Archimedean spiral to radiating structure during the uniform green-light exposure; scale bar, 50 µm.

Fig. 5. Photopatterning of rotational fingerprint superstructures. (a) Schematic of structured light exposure process. The intensity of the 365-nm light source is 10–140 µW/cm², and the lengths of purple arrows indicate the varied intensity of light. (b) Evolution of the fingerprint superstructure during the irradiation; scale bar, 50 µm; (c) relationships between the period of fingerprint stripes, rotational angle, and the exposure time.