Hydrogels are hydrophilic networks of polymeric chains that can retain a large amount of water. They are commonly used in applications ranging from soft robotics to bioprinting, and have proved useful in other applications that require a large amount of deformation, like transparent touch panels. The applications for hydrogels are limited, however, by their fabrication methods, which traditionally rely on molding and casting. These traditional fabrication methods limit the geometric complexity of the gels and result in relatively low resolution. There have been many recent developments in 3D printed hydrogels, but there are still limitations: they still don’t have very high resolution, geometric complexity or stretchability.
That could be changing, however. Researchers at the Singapore University of Technology and Design (SUTD) Digital Manufacturing and Design (DManD) Centre and the Hebrew University of Jerusalem (HUJI) have developed a family of highly stretchable and UV curable hydrogels that can be stretched by up to 1300%.
The hydrogels have been used to 3D print structures that require high printing resolution and high geometric complexity. They’ve also shown themselves to be highly biocompatible, which makes them promising for bioprinting and other medical applications.
“We have developed the most stretchable 3D printed hydrogel sample in the world,” said Assistant Professor Qi (Kevin) Ge from SUTD’s Science and Math Cluster, who is one of the co-leaders of this project. “The printed hydrogel sample can be stretched by up to 1300%. At the same time, the compatibility of these hydrogels with digital light processing-based 3D printing technology allows us to fabricate hydrogel 3D structures with resolutions up to 7 μm and complex geometries.”
“The printed stretchable hydrogels show an excellent biocompatibility, which allows us to directly 3D print biostructures and tissues,” continued Ge. “The great optical clarity of these hydrogels offers the possibility of 3D printing contact lenses. More importantly, these 3D printable hydrogels can form strong interfacial bonding with commercial 3D printing elastomers, which allows us to directly 3D print hydrogel-elastomer hybrid structures such as a flexible electronic board with a conductive hydrogel circuit printed on an elastomer matrix.”
The research was published in the most recent issue of the Journal of Materials Chemistry B and was also featured on the front cover.
“Overall, we believe the highly stretchable and UV curable hydrogels, together with the UV curing based 3D printing techniques, will significantly enhance the capability of fabricating biostructures and tissue, contact lenses, flexible electronics, and many other applications,” said Professor Shlomo Magdassi, who is a co-leader of this project at HUJI.
As research into hydrogels continues, more and more applications will open up, especially through 3D printing. Whether it’s bioprinting, 3D printed electronics, or others, these fascinating substances are progressing into more sophisticated uses. 3D printing has been used in the medical field to fabricate hydrogel constructs with complex geometries such as vascular networks, porous scaffolds, meniscus substitutes and others, and while many researchers still struggle to print these constructs with the required high resolution, this latest development is another step towards the kind of resolution and geometry that is needed.
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