Figure 4.

4D printed scales with a ‘weave’ bilayer architecture and with WPC raster pattern at 0° from the scale's longitudinal axis. Having the same 3D printed raster pattern for all three sets of samples (a), 4D scales show different shape deformations when fully wet (c) in response to changes to the bilayer constraints in both the longitudinal and lateral axis as well as the boundary edge of the scale (b). Samples with single constraints in either longitudinal or lateral directions (sets 2–4, B and C samples) had simple bending deformation perpendicular to the constraint direction, consistent with simple bilayer behaviour. Samples with constraints in both axes (sets 2–4, A samples) had a twist bending deformation. Samples with no axial constraints presented very limited shape change (sets 2–4, D samples). (Online version in colour.)