Exploring the biomedical significance of time-dependent design enabled by additive manufacturing

Lead Research Organisation: University of Birmingham
Department Name: School of Physics and Astronomy


Additive manufacture (AM) has the unique ability of creating the component material simultaneously with the geometry, something which is not possible with traditional subtractive manufacturing techniques. As such, this opens up the opportunity to vary how the material is produced, and therefore the intrinsic material properties, as the component is being built. This form of time-dependent design during manufacture, otherwise known as Temporal Design for Additive Manufacture (TDfAM) or sometimes called 4D printing, has the potential to afford a designer a new dimension of design freedom; being able to introduce heterogeneity of material or surface properties within a homogenous part.
AM also enables the manufacture of geometries that would otherwise be impossible to manufacture, for example: lattices. This is another way in which AM has the ability to afford a designer increased control over material properties, through the use of different lattice topologies. Not only does a lattice unit cell topology influence characteristics such as relative density and overall stiffness, but specification of different lattice topologies gives increased control over surface area to volume ratio, an important characteristic if considering degradation. As such, combining different lattice designs with bioresorbable materials can result in different variations in stiffness over time during degradation, resulting in a design that is time dependent during service.
This type of additional control and variation in properties over time could see many applications in areas where a time dependent response is required but manually actuating such a variation is difficult or impossible, such as in biomedical implants. In the case of fracture fixation, the optimum stiffness requirement varies over time: stability is required immediately after fracture but after approximately 6 weeks, interfragmentary motion governs the efficacy of healing. In this instance, changing the compliance of the fixation could offer enhanced healing, by enabling micromotion around the fracture site which changes over time. Using current methods, it is not possible to satisfy this changing and contradictory design requirement over time without the need for multiple surgeries, which would be more traumatic than its worth. Designing a fixation solution with tailored time-dependent stiffness that satisfies the varying stiffness requirements would solve these issues.
In this project this is achieved through the design and modelling of lattice structures additively manufactured from bioresorbable materials, such as zinc, looking specifically at the application of fracture fixation in a high tibial osteotomy as a case study. This project experimentally investigates the potential additional control over material and surface characteristics that TDfAM (variation of process parameters during the build) can afford a designer in a biomedical context; and also investigates bioresorbable lattices as a vehicle to enable time dependent design of stiffness within fracture fixation, through the use of design, finite element modelling and computational validation.

Planned Impact

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.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S02297X/1 01/07/2019 31/12/2027
2256386 Studentship EP/S02297X/1 01/10/2019 30/09/2023 Barnaby Hawthorn