Russian doll deployable meta-implants: Fusion of kirigami, origami, and multi-stability. (June 2020)

• Record Type: Journal Article
• Authors: Bobbert, F.S.L.; Janbaz, S.; van Manen, T.; Li, Y.; Zadpoor, A.A.
• Is Part Of: Materials & design. Volume 191(2020)
• Publication Date: 2020-06
• Subjects: Deployable structures -- Orthopaedic biomaterials -- Mechanical behavior -- Surface patterns; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2020.108624
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Deployable meta-implants aim to minimize the invasiveness of orthopaedic surgeries by allowing for changes in their shape and size that are triggered by an external stimulus. Multi-stability enables deployable implants to transform their shape from some compact retracted state to the deployed state where they take their full sizes and are load-bearing. We combined multiple design features to develop a new generation of deployable orthopaedic implants. Kirigami cut patterns were used to create bi-stability in flat sheets which can be folded into deployable implants using origami techniques. Inspired by Russian dolls, we designed multi-layered specimens that allow for adjusting the mechanical properties and the geometrical features of the implants through the number of the layers. Because all layers are folded from a flat state, surface-related functionalities could be applied to our deployable implants. We fabricated specimens from polylactic acid, titanium sheets, and aluminum sheets, and demonstrated that a deployment ratio of up to ≈2 is possible. We performed experiments to characterize the deployment and load-bearing behavior of the specimens and found that the above-mentioned design variables allow for adjustments in the deployment force and the maximum force before failure. Finally, we demonstrate the possibility of decorating the specimens with micropatterns. Graphical abstract: Unlabelled Image Highlights: Deployable and foldable meta-biomaterials were designed, manufactured, mechanically characterized. Foldable meta-biomaterials allow for the application of complex functional nanopatterns. Multi-layer Russian doll configurations withstand higher compression forces and offer enhanced tunability. A combination of origami and kirigami can be used to develop meta-implants with unusual functionalities.