Additive Manufacturing of Metal Structures at the Micrometer Scale

Abstract

Currently, the focus of additive manufacturing (AM) is shifting from simple prototyping to actual production. One driving factor of this process is the ability of AM to build geometries that are not accessible by subtractive fabrication techniques. While these techniques often call for a geometry that is easiest to manufacture, AM enables the geometry required for best performance to be built by freeing the design process from restrictions imposed by traditional machining. At the micrometer scale, the design limitations of standard fabrication techniques are even more severe. Microscale AM thus holds great potential, as confirmed by the rapid success of commercial micro-stereolithography tools as an enabling technology for a broad range of scientific applications. For metals, however, there is still no established AM solution at small scales. To tackle the limited resolution of standard metal AM methods (a few tens of micrometers at best), various new techniques aimed at the micrometer scale and below are presently under development. Here, we review these recent efforts. Specifically, we feature the techniques of direct ink writing, electrohydrodynamic printing, laser-assisted electrophoretic deposition, laser-induced forward transfer, local electroplating methods, laser-induced photoreduction and focused electron or ion beam induced deposition. Although these methods have proven to facilitate the AM of metals with feature sizes in the range of 0.1-10 µm, they are still in a prototype stage and their potential is not fully explored yet. For instance, comprehensive studies of material availability and material properties are often lacking, yet compulsory for actual applications. We address these items while critically discussing and comparing the potential of current microscale metal AM techniques.

Porous Titanium Implants: A Review

“…The group of DED methods include such commercialized techniques as direct metal deposition (DMD), laser engineered net shaping (LENS), and direct manufacturing (DM). [119][120][121] The PBF technologies allow for the manufacturing of high precision parts, such as dental or craniofacial implants. However, their size are limited by the working area.…”

Writing with Fluid: Structuring Hydrogels with Micrometer Precision by AFM in Combination with Nanofluidics

“…The transfer of macroscopic techniques down to the micrometer‐ and the nanometer‐scale has been pursued actively in recent years . Many of these new approaches are based on scanning probe techniques, in particular when dealing with nanometer‐sized structures . However, for soft materials, such as hydrogels, only a limited number of techniques are available, in particular techniques that would allow for a rapid and versatile prototyping process.…”

Nanostructure and Microstructure Fabrication: From Desired Properties to Suitable Processes

“…Droplet deposition methods are mainly used for depositing 2D patterns, resulting in structures of level‐2 geometric complexity. 3D structures can be fabricated in a layer‐by‐layer fashion, or in a sequential fashion to create, for example, wire‐like structures . The attainable resolution of droplet‐printing methods is limited by the droplet size, which is typically in the order of 100 nm .…”