Engineers have pioneered a new low-cost technique for 3D printing that allows structures that fold themselves into different shapes – this advance could improve how surgeons create bone implants.
The team – based at TU Delft in the Netherlands – combined traditional origami techniques and 3D printing to allow them to construct flat structures which self-fold.
If the goal is to create complex shapes, and it is, some parts should fold sooner than others… therefore, we needed to programme time delays into the material. This is called sequential shape-shifting Lead researcher Prof Amir Zadpoor
The technique works by alternating the thickness and alignment of each filament in the design.
This allows the engineers to create 2D-structures that can ‘shape-shift’ in a set order. This is important as it would allow future bone implants to have a porous interior. Something difficult to achieve with existing techniques when creating prosthetics.
Once the structure is created it acts as a scaffold and allows for a patient’s own stem cells to move into the porous interior of the implant. This means that bone grows throughout the implant, rather than just coating the exterior.
The result should be a durable stronger implant.
2D printing also allows delicate nanopatterns to be created to guide cell growth. These so-called ‘instructive surfaces’ allowed the team to encourage certain types of cell growth (for example; a pillar shape appears to encourage stem cells to become bone cells).
Currently, it is not possible to create these patterns on the inside of a 3D structure.
The team used Ultimaker 3D printer – a cheap hobbyist printer – and common printing materials. This means the implants cost only €17 per kilogram.
Published as Programming 2D/3D shape-shifting with hobbyist 3D printers in Materials Horizons.