Self-adjusting voxelated electrochemical three-dimensional printing of metallic microstructures

Abstract Microscale metallic structures enhanced by additive manufacturing technology have attracted extensive attention especially in microelectronics and electromechanical devices. Meniscus-confined electrodeposition (MCED) advances microscale 3D metal printing, enabling simpler fabrication of superior metallic microstructures in air without complex equipment or post-processing. However, accurately predicting growth rates with current MCED techniques remains challenging, essential for achieving precise structure fabrication and preventing nozzle clogging. In this work, we present a novel approach to electrochemical 3D printing that utilizes a self-adjusting, voxelated method for fabricating metallic microstructures. Diverging from conventional voxelated printing which focuses on monitoring voxel thickness for structure control, this technique adopts a holistic strategy. It ensures each voxel's position is in alignment with the final structure by synchronizing the micropipette's trajectory during deposition with the intended design, thus facilitating self-regulation of voxel position and reducing errors associated with environmental fluctuations in deposition parameters. The method's ability to print micropillars with various tilt angles, high density, and helical arrays demonstrates its refined control over the deposition process. Transmission electron microscopy (TEM) analysis reveals that the deposited structures, fabricated through layer-by-layer (voxel) printing, contain nanotwins, which are widely known to enhance material mechanical and electrical properties. Correspondingly, in situ scanning electron microscopy (SEM) microcompression tests confirm this enhancement, showing these structures exhibit a compressive yield strength exceeding 1 GPa. The indentation tests provided an average hardness of 3.71 GPa, which is the highest value reported in previous work using MCED. The resistivity measured by the four-point probe method was 1.95±0.01×10 -7 Ω·m, nearly 11 times that of bulk copper. These findings demonstrate the considerable advantage of this technique in fabricating complex metallic microstructures with enhanced mechanical properties, suitable for advanced applications in microsensors, microelectronics, and micro-electromechanical systems.