Additive Manufacturing of Nanoscale Multimaterial Voxels Via Meniscus-Confined Electrodeposition

Advanced applications featuring sub-microscale and nanoscale metallic structures, which include energy storage devices, nanophotonic elements, and nanoelectronic interfaces, require three-dimensional multimaterial structural elements. Here, we present an approach for highly localized meniscus-confined electrodeposition based on double-barrel nanopipettes capable of producing high-aspect ratio metallic structures with a wide range of elemental compositions. This is enabled by the possibility of finely tuning local ionic content directly inside the liquid meniscus by applying voltage bias between the barrels filled with different electrolytes. This provides a platform for fast switching between materials within a single voxel and the fabrication of smooth material gradients via tunable electrodeposition, which is also characterized by improved mass-transport and faster print rates. We demonstrate the capability of this approach by producing various arrangements of Cu-Au and Au-Pt voxels with ca. 200 nm lateral resolution, which are formed from fully dense (non-porous) polycrystalline metallic alloys with the evidence of metastable microstructural features.