Additive Manufacturing of Multi-Metal Microstructures by Localized Electrochemical Deposition Under Hydrodynamic Confinement

This study presents a device and method for multi-metal printing of microscale structures. The method is based on combining hydrodynamic confinement of electrolytes with localized electrochemical deposition (HLECD), allowing rapid switching of the deposited metal. The device used in HLECD integrates a micro-anode on a vertical microfluidic chip containing two open-ended channels that control the flow of electrolytes surrounding the anode. When placed on top of a conducting surface, a localized electrochemical reaction is initiated, wherein the deposited metal composition is dictated by the electrolyte in the confinement. A range of electrolytes, which are used to deposit copper, tin, silver, and nickel, are used to fabricate multiple structures involving more than 60 material changes within a single printing process. The structures are analyzed using electron microscopy, showing the ability to achieve sharp transitions between pure metals. The constant replenishment of electrolytes also eliminates the problem of ion depletion commonly occurring in localized electrochemical deposition, and enables printing rates that are nearly an order of magnitude greater. This work presents 3D printing of multi-metal microstructures, enabled by combining hydrodynamic flow confinement with localized electrochemical deposition. The printing head is composed of a micro-anode located between two microchannels that control the electrolyte composition surrounding the electrode. In addition to real-time metal switching, the method alleviates ion depletion and enhances deposition rates compared to standard localized electrochemical deposition.image