Fig. 4: Halftone pattern-regulated mechanical strain mapping via DIC analysis. | Nature Communications

Fig. 4: Halftone pattern-regulated mechanical strain mapping via DIC analysis.

From: Halftone-encoded 4D printing of stimulus-reconfigurable binary domains for cephalopod-inspired synthetic smart skins

Fig. 4

Optical images and x-strain mapping of deswollen hydrogel films (35 °C water) encoded with G3 (grayscale level) halftone patterns oriented at 0° (a), 45° (b), and 90° (c) under 30% strain \({\varepsilon }_{x}\). d Stress-strain curves of deswollen hydrogel films corresponding to (a–c). e Encryption of the letters “PSU” by rotating local halftone pattern 30° relative to the x-axis. f Optical image of the encrypted hydrogel film in its deswollen state. x-strain (g) and y-strain (h) mappings under 5% strain (\({\varepsilon }_{x}\) and \({\varepsilon }_{y}\)) along the x- and y-axes, respectively. i Stiff re-entrant honeycomb meta-structure (G9 halftone) embedded in a soft film (G1 halftone). j Optical image of the meta-patterned film in its deswollen state. y-strain (k) and x-strain (l) mappings under y-axis loading. m Strain profiles along a marked linear pathway X. Scale bars, 500 μm (a–c), 5 mm (f–h, j–l).

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