Precise 3D printing at high speed

3D printers working in the millimetre range and larger are increasingly used in industrial production processes — but many applications require precise printing on the micrometre scale at a far higher speed. Now, researchers of Karlsruhe Institute of Technology (KIT) have developed a system to print highly precise, centimetre-sized objects with submicrometre details at a speed that is apparently unmatched. Their work has been described in the journal Advanced Functional Materials.

For this type of 3D printing, the beam of a laser passes a liquid photoresist in a computer-controlled manner. The material located in the focus of the laser only is exposed and hardened.

“The focal points correspond to the nozzles of an inkjet printer, the only difference being that they work three-dimensionally,” said Vincent Hahn, first author of the study. In this way, highly precise filigree structures can be produced for various applications, such as optics and photonics, material sciences, bioengineering and safety engineering.

The 3D counterpart of a pixel or 2D picture element is called a voxel. Typically, several hundred thousands of voxels per second are produced with a single laser light spot. This means the process is nearly a hundred times slower than graphical inkjet printers, which has impeded many applications so far.

Scientists from KIT and Queensland University of Technology (QUT) used special optics to divide the laser beam into nine partial beams that focus on a focal point each. All nine partial beams can be used in parallel and, thanks to improved electronic control, they can be moved precisely and rapidly.

This and some other technical improvements made the researchers reach 3D printing speeds of about 10 million voxels per second, which corresponds to the speed reached by graphical 2D inkjet printers. To demonstrate the speed as well as the reliability of their set-up, the researchers printed a lattice structure of 60 mm³ in size, with details down to the micrometre scale, containing more than 300 billion voxels.

“We have by far outperformed the record reached by 3D-printed aircraft wings. This is a new world record,” said Professor Martin Wegener, spokesperson of the 3D Matter Made to Order (3DMM2O) Cluster of Excellence within which the system was developed.

KIT will continue research and development work in this area, with Hahn noting, “After all, 3D printers will be used to print not just one page, but thick volumes.” This will also require progress in chemistry, as more sensitive photoresists are needed to generate more focal points at the same laser output, for example.

Image caption: The metamaterial printed with the new system consists of a complex three-dimensional lattice structure on the micrometre scale. Image credit: Vincent Hahn, KIT.

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