PANI coating on Au NPs
Preparation of eNPoM
DLS and SEM analysis
Single-particle optical DF imaging and spectroscopy
Electrochemical cell
Numerical simulation
The coating of the eNPoM metasurface was carried out using a constructed convective coating setup (26). The evaporated Au substrate was cleaned with oxygen plasma and attached onto a motorized translation stage (ProScanII). A volume (ca. 40 μl) of the colloidal PANI-coated Au NPs was dropped onto the Au substrate. A fixed fluoro-silanized glass plate was positioned ~300 μm above the liquid to precisely confine the liquid during the coating. By moving the translation stage supporting the Au substrate at a constant speed of 1 μm/s, a liquid meniscus was formed on one edge and subsequently dragged across the substrate, accumulating and coating with nanoparticles. The fill fraction of the final metasurface was controlled by adjusting the volume fraction of the initial colloidal suspension.