Route to three-dimensional metallized microstructures using cross-linkable epoxide SU-8

High-quality silvered polymeric 3D microstructures based on multiphoton Direct Laser Writing (DLW) using cross-linked epoxide SU-8 followed by surface functionalization and electroless metal deposition were created. The silver coated SU-8 microstructure was produced by immersing a Au-NP functionalized sample in a Ag ion bath containing gum arabic for 14 min. Control experiment results show that Ag is only deposited when the expoxide SU-8 structure is subjected to both surface amination and Au-NP functionalization, which is consistent with the surface-bound Au-NPs catalyzing initial metal deposition. The nanoscale morphology of Ag is found to be controlled through concentration of Ag ions in the bath as high Ag ions concentration generates rice-shaped morphology while lower Ag ions concentration produces Ag grains having spheroidal morphology.