Why would you want to 3D print in water? New research into materials shows a novel technique with applications for 3D bioprinting.
Materials scientist Shlomo Magdassi, who recently featured in our Future of 3D Printing guest series, has led research into a new family of photoinitiators for use in digital light processing (DLP). These additives, that cause rapid solidification of a liquid material, create faster reactions when exposed to light.
By 3D printing in water, it also opens up the DLP method to medical applications, leading toward a competitive response for patient specific implants and tissues.
3D printing in water?
When working with living cells, hydrogels and bioscaffolds are typically used as support material to grow tissue. As such, there is a growing volume of 3D bioprinting research concerning the optimal environment and materials for cell growth.
With this in mind, it becomes clear why water may be a good environment to 3D print a structure for medical use.
As arguably “the most versatile” 3D printing method in terms of design flexibility and speed Magdassi, and respective teams at the Hebrew University of Jerusalem and University of Maryland, focus on photopolymerization for 3D printing in water.
Finding the balance between activity and dissolution
The challenge of 3D printing in water is finding an initiator, i.e. the active ingredient that reacts upon exposure to light, that also dissolves at the right moment.
Most photoinitiators are consumed by irradiation in the 3D printing process. By contrast, the key to rapid 3D printing of Magdassi’s initiators is in their ability to split water, and absorb oxygen molecules that typically inhibit the performance of the process.
The particles added as the photoinitator in this case are semi-conductive metal hybrid nanoparticles (HNPs), and are used to create high-resolution 3D objects on a sub-microscopic scale.
As seen in the cart below, degree of polymerization in material including the HNPs is significantly faster than light-restive material used without the particles.
Discussion and further research
The team of scientists found that,
The semiconductor and metal segments can be tuned in terms of their composition, size, shape, and relative location toward optimal performance in photopolymerization and in particular in 3D printing.
The full paper, Rapid Three-Dimensional Printing in Water Using Semiconductor− Metal Hybrid Nanoparticles as Photoinitiators, discussed in this article is published online in the journal NanoLetters. It is co-authored by Amol Ashok Pawar, Shira Halivni, Nir Waiskopf, Yuval Ben-Shahar, Michal Soreni-Harari, Sarah Bergbreiter, Uri Banin, and Shlomo Magdassi.
Other research conducted by Magdassi at the Hebrew University of Jerusalem, and colleagues at the Singapore University of Technology and Design, includes the invention of the “most stretchable” for DLP 3D printers.
Featured image: Illustration of the nanoparticle additions to a material used for high-resolution DLP 3D printing. Image via Nano Letters.