Aug 1, 2017 | By Benedict

Researchers at the Center for Nanoscience and Nanotechnology at the Hebrew University of Jerusalem have developed a new kind of photoinitiator for digital light processing (DLP) 3D printing in water. The photoinitiators could be used to make bio-friendly 3D printed structures.

At first, 3D printing in water doesn’t seem like the most intuitive idea. In fact, it might bring up images of a horrible, congealed mess of plastic. But some experts believe that 3D printing in water could offer an environmentally friendly approach to additive manufacturing, one that produces high-quality hydrogels, bioscaffolds, and other useful things.

In a paper titled, “Rapid Three-Dimensional Printing in Water Using Semiconductor− Metal Hybrid Nanoparticles as Photoinitiatorswriting,” Prof. Uri Banin and Prof. Shlomo Magdassi at the Hebrew University's Institute of Chemistry have described an efficient means of light-based 3D printing in water. The professors were joined by several other researchers, including scientists from the University of Maryland.

The group’s method uses semiconductor-metal hybrid nanoparticles (HNPs) as photoinitiators, water-soluble molecules that induce the chemical reactions which solidify printed material through light. The research paper has been published in Nano Letters.

The Israel-based researchers say that 3D printing in water could improve biomedical 3D printing, especially the fabrication of medical devices and 3D printed scaffolds for tissue engineering. They believe that joint replacements, bone plates, heart valves, artificial tendons and ligaments, and other artificial organ replacements could all benefit from water-based 3D printing.

But the researchers don’t just believe that any old water 3D printing method will improve biomedicine. Rather, they say that their new hybrid nanoparticles offer distinct advantages for making the process a success.

These advantages include tunable properties, a wide excitation window in the UV and visible range, high light sensitivity, and a unique photocatalytic mechanism that increases 3D printing efficiency while reducing the amount of materials needed.

Regular light (c), fluroscence (d), and scanning electron microscopy (e) images of 3D printed structure made with HNP photoinitiator

“Unlike current water-compatible photoinitiators, HNPs exhibit high absorption cross sections at operating wavelengths of commercially available digital light processing printers, resulting in fast polymerization and printing,” the researchers explain.

The Hebrew University of Jerusalem scientists say that the HNPs’ function as photoinitiators “is uniquely based on a photocatalytic mechanism to form radicals while consuming dissolved oxygen, enabling their use in 3D printing at ambient conditions.”

The HNPS differ in important ways from common organic photoinitiators, as they are not consumed during the light irradiation. Moreover, due to their “giant two-photon absorption cross section,” they can be used to 3D print submicron objects at a very high resolution.

Ultimately, the Center for Nanoscience and Nanotechnology researchers believe that their work could be used to improve 3D printing across several areas.

“We envision high potential for further realization of HNPs as PIs UV curable inks and in 3D printing applications,” they write.



Posted in 3D Printing Technology



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