Joining Forces - Lightning-Fast 3D Microprinting With Two Lasers

Researchers of the Cluster of Excellence "3D Matter Made to Order" print microstructures by crossing red and blue laser beams - publication in Nature Photonics

The goal of many 3D printing processes is to print plastic objects precisely, quickly and cost-effectively. However, speed and high resolution are still a technological challenge. A research team from the Karlsruhe Institute of Technology (KIT), the University of Heidelberg and the Queensland University of Technology (QUT) has come a long way towards this goal. It developed a laser printing process that can print micron-sized parts in the blink of an eye. The international team published the work in Nature Photonics . (DOI: 10.1038/s41566-022-01081-0).

Stereolithography 3D printing is currently one of the most popular additive manufacturing processes for plastics, both for private and industrial applications. In stereolithography, the layers of a 3D object are sequentially projected into a resin-filled container. The resin is cured by UV light. However, previous stereolithography processes are slow and the resolution is too low. The 3D light sheet printing used by the KIT researchers is a fast and high-resolution alternative.

3D printing with two colors in two stages
In "light sheet 3D printing," blue light is projected into a container filled with a liquid resin. The resin is pre-activated by the blue light. In a second stage, a red laser beam provides the additional energy required to cure the resin. However, only resins that quickly return from the pre-activated state to their original state can be printed quickly in 3D printing. Only then can the next layer be printed. The return time consequently dictates the waiting time between two consecutive shifts and therefore the printing speed. "With the resin we used, the return time was less than 100 microseconds, which enables high printing speeds," says first author Vincent Hahn from the Institute for Applied Physics (APH) of KIT.

Micrometer-sized structures in just a blink of an eye
To take advantage of this new resin, the researchers built a special 3D printer. This printer uses blue laser diodes to project images into the liquid resin using a high-resolution, high-frame-rate display. The red laser is formed into a thin "light sheet" beam and crosses the blue beam perpendicularly in the resin. With this setup, the team was able to print micron-sized 3D parts in a few hundred milliseconds, in the blink of an eye. But it shouldn't stop there: "With more sensitive resins, we could even use LEDs instead of lasers in our 3D printer," says Professor Martin Wegener from the APH. "Ultimately, we want to print centimeter-sized 3D structures while maintaining micron-level resolution and high printing speed. "

The publication was created as part of the joint excellence cluster "3D Matter Made to Order" of KIT and Heidelberg University. Participating from the University of Heidelberg was junior professor Dr. Eva Blasco, head of a working group at the Organic Chemistry Institute and at the Institute for Molecular Systems Engineering and Advanced Materials.

Cluster of Excellence "3D Matter Made to Order"
In the "3D Matter Made to Order" cluster of excellence, scientists from the Karlsruhe Institute of Technology (KIT) and the University of Heidelberg are conducting interdisciplinary research on innovative technologies and materials for digitally scalable additive manufacturing in order to increase the precision, speed and performance of 3D printing to enhance. The aim of the work is to completely digitize 3D production and material processing from the molecule to the microstructure. In addition to funding as a cluster of excellence as part of the federal and state governments' excellence strategy competition, "3D Matter Made to Order" is funded by the Carl Zeiss Foundation.

More information on the Cluster of Excellence "3D Matter Made to Order"

Details on the KIT Center for Materials Research

Founded in 1386, Ruperto Carola is an internationally oriented research university whose range of subjects includes the humanities, social sciences and law as well as natural sciences, engineering and life sciences including medicine. Its successes in the excellence competitions - it belongs to the group of German universities of excellence - as well as in international rankings prove its leading role in the scientific landscape. Heidelberg University sees itself as continuing to develop outstanding individual disciplines, to strengthen interdisciplinary cooperation and to disseminate the results of its research to society.

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