for my third year individual project, I designed and prototyped a biocompatible aortic valve scaffold with natural histoarchitecture, using 3D printing. This project was far from my skillset, and challenged me as an engineer to learn more about a different field. With tissue engineering technology advancing, the aim of this project was to develop a novel valve that replicates the histoarchitecture of the native aortic valve, that could facilitate new tissue growth and regeneration.
This could revolutionize the landscape of long term aortic heart disease treatment, removing the need for lifelong anticoagulants and rejection.
This project opened my eyes to the role that engineering and design can play within the healthcare system and the profound differences it could have on patient recovery and life span. This challenged my design thinking as a product designer, and made me more flexible. The need for constant iterations and retesting when working on a microscale consolidated that not all projects are linear, and that setbacks can be a significant tool for learning if approached positively.
This project intended to improve upon previous literature, maintaining the ability for production by additive manufacturing. To accomplish this, a literature review was conducted to develop topic knowledge; notably, aortic valve microstructure and tissue engineering. Additive manufacturing techniques were also explored, ensuring that the scaffold considered printing limitations.
Initial Designs for the Aortic Leaflet (left) and Root Wall (Right) UECs
Many iterations for the repeated unit ECM cells (UECs) were required for both the aortic leaflets and aortic wall, as they are structurally different.
Final Aortic wall (left) and leaflet (right) UEC models
After the unit ECM cells were finalized, and a macroscale CAD model of the aortic root (leaflets and wall) was completed, they were combined. Using topology software the individual unit ECM cells were repeated across the root model.
Ntopology images of final CAD model for additive manufacture
A microstructure CAD model of the scaffold was developed; a model of the aortic root and the root’s native histoarchitecture, closely replicating the collagen and elastic fibres that comprise the extracellular matrix.
TDS resin print (Left) and 'Flexible' TPU print (right)
After testing the 3D printing technologies available within the scope of this project, the scaffold was successfully printed using a FormLabs SLA printer. The printed scaffold was extremely delicate and brittle, especially the leaflets, and shattered in testing.
After research and discussion with lab technicians, ‘flexible’ TDS resin was used, possessing a softer, more pliable texture. This scaffold possessed outstanding flexibility, which to the touch resembled the suppleness of native tissue examined during porcine testing. The FormLabs printer maintained a decent resolution, despite the reduced fibre diameter.
Uniaxial testing conducted on Porcine aortic leaflets (Left) and the TPU scaffold root wall (right)
Testing was conducted, for comparison of mechanical properties against porcine aortic valve tissue and results yielded conclusive findings that developing aortic scaffolds of this nature is feasible, limited only by print resolution and material selection.
