Translating the Three-Dimensional Mathematical Modelling of Plant Growth to Additive Manufacturing

Much like how plants grow via the expansion and multiplication of cells, a 3D printed component is formed via the bonding of material point-by-point from the bottom-up. Exploiting this analogy, this work employs mathematical models of three-dimensional plant growth to further understand and aid implementation of additive manufacturing (AM) technologies (otherwise known as 3D printing). The resolution of these printed structures is of the upmost importance in the fabrication of tissue scaffolds or constructs that mimic the mechanical properties of tissues. As such, the overarching aim is to derive a generalised mathematical model to simulate the extrusion-based bioprinting process via manipulation of the underlying physics of the system. Such a model has the potential to theoretically identify which combinations of printing process parameters generate a successful resolution: the 'window of printability' of a bioink.

A hydrogel typically presents a shear-thinning behaviour. In this thesis we begin by considering the simplest case: a Newtonian fluid flow far from any edge effects. We achieve this via derivation of a steady-state model for a viscous thread under extrusion using an arc-length-based coordinate system. This initial model remains an important milestone in our work towards the non-Newtonian model; providing us with a strong framework upon which non-Newtonian extensions can build. With this in place, we intend to iteratively relax assumptions on the viscosity and surface tension, enabling the model to gradually converge towards the real system as well as provide any justification for effects assumed negligible in the modelling process. We plan to employ experimental techniques to provide validation at each milestone.

This uniquely transdisciplinary methodology seeks to optimise the comparability and transferability of results across materials and laboratories and, above all, extend the creativity and efficiency of Design for AM by devising a user-friendly, sustainable tool for engineers to visualise AM as a process of growth.

1. Our primary impact will be by supplying the UK knowledge economy with skilled multidisciplinary researchers, equipped with the technical and transferable skills to establish the UK as pre-eminent in topology-based future technologies. The training they receive will make them proficient in the demands of the translation of academic science (with a broad background in condensed matter physics, materials science and applied electromagnetics) to industry, with direct experience from internship and industry engagement days. With their exposure to both theoretical research (including modelling and big data-driven problems) and experimental practice, our graduates will be ideally equipped to tackle research challenges of the future and communicate to a broad audience, ready to lead teams made up of diverse specialised components. The potential impact of our researchers will be enhanced by a broad programme of transferable skills, focusing on innovation, entrepreneurship and responsible research. Beneficiaries here will include the students themselves as they embark on future careers intertwining academic research and industry, as well as the other sectors listed below.

2. The research undertaken by students in the CDT will have impact on the future direction of topological science. Related disciplines, including physics, materials science, mathematics, and information technology will benefit from the cross-disciplinary fertilisation it will enable. The CDT will not only provide an interface between research in physical sciences and engineering, but also provide a route for academia to interact effectively with industry. This will help organise researchers from different disciplines to collaborate around the needs of future technology to design materials based on topological properties.

3. Our research will enable industries to set the direction of topological research around the needs of commercial research and development, leading to wealth generation for the UK, and to influence the mindset of the next generation of future technologists. Specifically, topological design has the promise to revolutionise devices and materials relevant to communications, microwave and terahertz technologies, optical information processing, manufacturing, and cybersecurity. Through partnership with organisations from the wider knowledge sector, we will deepen the relationship between academic research and disciplines including IP law and scientific software development.

4. Our CDT will also have impact on the wider academic community. New specialist courses and training in transferable skills will be developed utilising cutting-edge multimedia technologies. Our international research collaborators, including prominent global laboratories, will benefit from placements and research visits of the CDT students. Our interdisciplinary research, combining the needs of academia and industry will be an exemplar of the effectiveness of the CDT model on an international stage.

5. The wider community will benefit from our organised public engagement activities. These will include direct interaction activities, such as demonstrating at the Birmingham Thinktank Science Centre, the Royal Society Summer Exhibition, local schools and community centres.