Researchers of the TU Delft combine the technology of 3D printing with self-folding flat surfaces to simplify the placement of medical implants. This research stems from a study of the Maastricht UMC+ on “smart” 3D printed implants to restore bone defects with.
This TU Delft research concerns the developing of flat surfaces that can be 3D printed and then “learn” how to fold themselves later on. A sort of origami-technique. These materials have a potential to be extremely suitable for a broad scala of medical implants. The findings of the researchers have been published as the cover story of Materials Horizons October 24 edition.
Holy Grail of Tissue Culture
Complete regeneration of functional tissue is – according to the TU Delft – the holy grail of tissue culture. Realizing this may revolutionize the treatment of many diseases. Often, there are multi functional biomaterials needed for effective tissue regeneration. A broad study lead by the MaastrichtUMC+ is only one of a number of researches done in this area. This project kicked off in October and if it is a succes, it would mean faster recovery and fewer operations for many patients.
The applications of 3D printed bio-implants even go beyond the repair of bone defects, says dr. Amir Zadpoor. The researcher at TU Delft works in the field of medical 3D printing applications and he is working closely with Dutch academic hospitals like the LUMC, UMC and the AMC.
3D Structures and Nanopatterns
“In the ideal case biomaterials are optimized in terms of their 3D-structure and as for the nanopatterns on their surface,” according to Zadpoor. “With 3D printing it is possible to create very complex 3D structures, but the ability to influence the surface is quite limited during the 3D print process. Nanolithography techniques can generate very complex nanopatterns, but generally only on flat surfaces. There didn’t existed a way yet to combine arbitrarily complex 3D-structures with arbitrary complex nanopatterns on the surface.”
Zadpoor came up with a solution to this impasse using origami, the traditional Japanese art of paper folding. First, the flat surfaces are 3D printed in a spacial way: they learn ow to fold themselves. The surface is then fitted with complex nanopatterns. As a final step, the self-folding mechanism is activated (by for instance temperature changes), so the flat surface can fold itself and complex 3D structures arise.
Activation Mechanisms Imitated
Nature uses several activation mechanisms to program complex transformations in the shape and functionality of living organisms. Inspired by exactly that process, the team of Zadpoor (including researchers S. Janbaz and R. Hedayati) developed programmable materials that firstly are two-dimensional. When they are stimulated by e.g. temperature changes, they can change shape by themselves and take on complex three-dimensional geometry.
There are various combinations of two or more layers of shape memory polymer (SMP) and hyper-elastic polymers used to program four basic shape changes, including self-winding, self-twisting, combined self-winding and -wrinkeling, and the formation of wave-shaped strips. Some transformations are then integrated with other two-dimensional structures with self-twisting constructions inspired by DNA. Programmed pattern development in cellular solids, self-folding origami and self-organizing fibers as a result.
“Our work is only a small step towards better medical implants,” says Zadpoor, “but the progresses we make are inspiring.”