3D Micro-Printing Goes Macro

During the last twenty years, multiple technologies have been developed by means of 3D direct laser writing. In an article published recently, Sofía Rodríguez and Andreas Frölich put a special focus on fast additive manufacturing based on two photon-polymerization (2PP). This 3D direct laser writing technique allows for building nano-, micro- and millimeter-sized objects of almost any desired shape with easy processes along a classical 3D printing workflow using photopolymerizable resins as printable matter. For this purpose, tailor-made 2PP resins have been specially designed in order to meet the desired final attributes of the printed object such as resolution, surface roughness, specific chemical and mechanical properties and, not least, printing time.

Highest-precision 3D printing: Closely packed microlens array with 100 % filling factor. (Source: Nanoscribe)

The German company Nanoscribe provides 3D printing systems based on 2PP and tailor-made print materials. Its Photonic Professional GT 3D printers are used for the fabrication of complex three-dimensional parts with resolutions down to less than 1 µm, which are difficult to make with conventional microfabrication methods and established 3D printing techniques. 2PP targets the requirements of design freedom in three dimensions, fast development iteration cycles and sub-micrometer accuracy, which are needed in microfabrication for photonics and optics, precision and medical engineering as well as in the MEMS industry.

Engineers and designers encounter challenges such as high precision and high throughput when dealing with the fabrication of 3D objects of millimeter dimensions in reasonably short printing times. When a resolution of a few micrometers is sufficient and rapid fabrication is of prime importance, the right choice of material can impact the printing throughput positively. For example, novel resins are suitable for creating mechanical components with increased writing speed. In this field of precision engineering there is the need to incorporate functionality in mechanical devices through precisely fabricated structural features which demand a high degree of design versatility in three dimensions. 2PP even offers a sufficiently high shape accuracy to fabricate a set of structures that can be assembled together. A screw and a corresponding nut represent matching printed parts. Each component was printed separately. The thread on the screw has an outer diameter of 1.3 mm which matches the thread on the nut perfectly in order to mount them to each other. Further application fields in the mesoscale include molds that could be used for serial replication in other materials in order to speed-up the fabrication at the industrial level.

Mesoscale fabrication: Screws and corresponding nuts. (Source: Nanoscribe)

In further technology sectors ranging from optical instrumentation to consumer electronics, devices make use of micro-optical components. Above all, high precision, shape accuracy and smooth surfaces are key requirements for the best optical performance of micro-optics. These are great challenges to master, especially when cost-effective and reliable serial production are at stake. Additive manufacturing can target these needs while being free of the use of mechanical tools, thus avoiding common limitations when producing vertical slopes, internal sharp edges and angles needed in optical shapes. By means of 2PP and a printable material designed for smooth surfaces and high shape accuracy, it is possible to create micro-optics with a surface roughness even better than 10 nm Ra and a shape accuracy better than 1 µm. Micro lenses, prisms, corner cube arrays and other freeform optical elements can thus be fabricated in an additive way significantly reducing design constraints known from subtractive techniques.

Due to novel materials for mesoscale fabrication, Nanoscribe’s systems push 3D microprinting to its limits. The range of applications, e.g. in the fields of micro rapid prototyping, micro-robots, micro-optics, as well as in photonics grows further while narrowing the previous gap between micro and macro 3D printing. (Source: Nanoscribe)

Reference: S. Rodríguez & A. Frölich (Nanoscribe): 3D Micro‐Printing Goes Macro, Laser Tech. J. 14(5) November 2017; DOI: 10.1002/latj.201700027

Link: Nanoscribe GmbH, Eggenstein-Leopoldshafen / KIT Campus North, Germany

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