Abstract
We describe our force-controlled 3D printing method for layer-by-layer additive micromanufacturing (µAM) of metal microstructures. Hollow atomic force microscopy cantilevers are utilized to locally dispense metal ions in a standard 3-electrode electrochemical cell, enabling a confined electroplating reaction. The deflection feedback signal enables the live monitoring of the voxel growth and the consequent automation of the printing protocol in a layer-by-layer fashion for the fabrication of arbitrary-shaped geometries. In a second step, we investigated the effect of the free parameters (aperture diameter, applied pressure, and applied plating potential) on the voxel size, which enabled us to tune the voxel dimensions on-the-fly, as well as to produce objects spanning at least two orders of magnitude in each direction. As a concrete example, we printed two different replicas of Michelangelo’s David. Copper was used as metal, but the process can in principle be extended to all metals that are macroscopically electroplated in a standard way.
Highlights
We describe our force-controlled 3D printing method for layer-by-layer additive micromanufacturing of metal microstructures
In the case of meniscus-confined electroplating (MCEP), which is performed in an atmosphere with controlled humidity, a glass pipette containing the metal ion solution and equipped with a counter electrode (CE) is moved toward the WE until a meniscus is formed between them
For better fitting of the vertical growth data using the experimental values of pillar diameters Rexperiment(p), we introduced an empirical scaling coefficient that allows estimation of the radius of the area where ions are collected Rfit(p): R
Summary
At the macro- and mesoscale (down to 100 μm), additive manufacturing (AM) of metal objects is recurrently performed with robust methods like selective laser and electron beam melting, both relying on the local fusion of metal particles to obtain a solid metal with the desired shape [1,2,3,4,5]. Since in this contribution we are presenting results obtained via local electrochemical (ec) reduction, we would like to focus on the techniques of this category Their common underlying idea is to fill a printing nozzle (in most cases a pipette) with a solution containing a metal salt, to bring it as close as possible to a biased conductive substrate (generally connected as working electrode, WE), and to eject the solution inducing a confined metal plating because of the vicinity of the nozzle with the working electrode. Upon immersion in a standard three-electrode ec cell, the ion tip could be used as nozzle for local supply of precursor ions (copper), confining their ec reduction on the cathodically polarized WE [49] This elicited a novel protocol for 3D μAM of metal structures [36]. Publications [36,51] and presenting complementary unpublished results
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