Researchers at Lawrence Livermore National Laboratory (LLNL) recently discovered a way to enhance two-photon lithography (TPL), a nanoscale 3D printing method. The research would enable doctors to carry out X-ray CT scans to analyze 3D printed implants within the body of a patient.

In a few words, TPL is a 3D printing technique that can produce nanoscale features smaller than one-hundredth the width of a human hair and LLNL’s discovery has extended this potential.

LLNL researchers can print woodpile lattices with submicron features a fraction of the width of a human hair. [Images: Jacob Long and Adam Connell/LLNL]
Entitled “Radiopaque Resists for Two-Photon Lithography To Enable Submicron 3D Imaging of Polymer Parts via X-ray Computed Tomography,” the paper explained how researchers cracked the code on resist materials improved for TPL and formed 3D microstructures with features less than 150 nanometers.

With traditional techniques, structures would be built from the ground up, limiting the size of the object because the distance between the glass slide and the lens was typically 200 microns or less. With the resist material placed on the lens and by focusing the 3D printer’s laser through the resist, it is therefore possible to 3D print microstructures with characteristics smaller than 150 nanometers but still multiple millimeters in height.

However, this is only a part of the research. The researchers also discovered how to improve the attenuation of the photopolymer resists used in the 3D printing process by more than 10 times, increasing (or decreasing) the number of X-rays the resists are able to absorb. Indeed, thanks to the index matching, the team explained that TPL could probably be used to 3D print much larger parts, with features as small as 100 nanometers.

3D printed octet truss structures with submicron features

It’s a very small piece of the puzzle that we solved, but we are much more confident in our abilities to start playing in this field now,” Saha said. “We’re on a path where we know we have a potential solution for different types of applications. Our push for smaller and smaller features in larger and larger structures is bringing us closer to the forefront of scientific research that the rest of the world is doing. And on the application side, we’re developing new practical ways of printing things.

D printed woodpile lattices with submicron features

You can read the whole research here. Sourabh K. Saha, James S. Oakdale, Jefferson A. Cuadra, Chuck Divin, Jianchao Ye, Jean-Baptiste Forien, Leonardus B. Bayu Aji, Juergen Biener, and William L. Smith are the authors of the paper.

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