Fig. 4.

Tailored local materials properties via the design of the chemical architecture. Exploiting the dissimilar nobility of Cu and Ag for (a–c) printing of sacrificial support structures and (d–h) tuning of local porosity and thus local mechanical strength. a Ag lines printed on top of Cu support structures before and (b, c) after selective wet etching of Cu. Scale bars (a–c): 5 μm. d Bi-metal pillars printed with alternating segments of Ag and Cu–Ag before and (e) after selective dissolution of Cu. The dealloying of Cu from the Cu–Ag segments renders partially nanoporous Ag pillars with soft (porous, coloured in yellow) and hard segments. f The step-function in porosity modulates the local mechanical strength: upon bending of the pillars, the plastic deformation is pronouncedly confined in the porous segments (Supplementary Movie 3). Scale bars (d–f): 1 μm. g, h Close-up of the partially nanoporous pillars after dealloying. Scale bars: 500 nm