Extended Data Fig. 3: Post-contraction properties of WRAP films.

a, Water content of wet IC/PEO film (elongation ratio, 0%) and PC-WRAP films increased with the elongation ratio increased. b, EIS spectra of wet IC/PEO film and PC-WRAP films (elongation ratio from 218% to 700%) show impedance decreased with elongation ratio increased. However, for elongation ratios > 400%, the decrease in impedance is smaller. All samples had the same exposed area (1.40 cm²) in PBS. c, Stress-strain curves show PC-WRAP films with elongation ratio between 218% and 400% broke at around 600% strain while those with larger elongation ratios broke at lower strains, indicating that stretchability decreased at elongation ratio >400%. d, Surface (right) and cross-section (left) FESEM image of freeze-dried post-contraction wet WRAP hydrogel thin film show typical porous structure. e, Viability/cytotoxicity assay showing the number of live normal human dermal fibroblasts cells after culturing 24 h in conditioned medium (prepared by soaking WRAP-400% in pristine culture medium) is comparable with cells cultured in pristine medium (control). f, Water induces instant shape-adaptive wrapping of WRAP-400% film around a stainless-steel rod. The WRAP film loosely slung around the rod contracts within seconds upon wetting. g, Supercontraction force generated by constrained WRAP-400% shows a transient behavior with 60% decaying within 10 seconds and only 5% remaining after 20 min. Inset: schematic of the test set-up. Testing gauge length was fixed at 0.6 L₀, where L₀ is the original length of WRAP-400%. Scale bar: 10 µm (d); 100 µm (e); 2 mm (f). Data in a, e are presented as mean ± s.d. from 4 samples. All experiments in d, e were repeated 3 or 4 times with similar results.