Design framework for 4D printing of shape morphing structures for biomedical applications

Four-dimensional (4D) printing is an innovative fabrication approach in which additive manufacturing (AM) technologies are used to fabricate structures that can evolve over time when exposed to a predefined external stimulus. (e.g., temperature, pH, electric field). The aim of this PhD thesis is the expansion and consolidation of 4D printing as an enabling manufacturing technology to program the environmentally triggered physical evolution of structures and devices of biomedical interest. Firstly, a theoretical study was performed to define a systematic methodology to design with 4D printing, exploiting the morphological box method. Then, the aforementioned theoretical tools were exploited for the design, fabrication and validation of four different cases of study of biomedical interests with the 4D printing approach: i) an active scaffold for trachea engineering; ii) a neural tube in vitro model; iii) tubular clips for sutureless intestinal anastomosis; iv) core-shell coiled structures for intestinal distraction enterogenesis. These devices highlighted the importance and potentiality of the developed theoretical framework, and, overall, of 4D printing as breakthrough technology, representing an enabling tool to address unsolved clinical needs in tissue engineering, and medical devices manufacturing by the combination of active materials with appropriate three dimensional architectures and advanced AM technologies.