Smart Manufacturing of Medical Devices for soft tissue fixation

We will research smart manufacturing routes, which impart controllable enhancement of properties and functionality of polymers and polymer composites whilst achieving precision geometry products. These will be relevant to a range of potential medical devices, selected with our industry partners, Zmith * Nephew, Wittman Battenfeld and Corbion Purac, particularly those exploiting shape memory functionality and surface feature control. The initial focus is for soft tissue fixation to bone (e.g. rotator cuff and anterior cruciate ligament (ACL) repairs); longer-term goals include fixations for fracture (including intermedullary nails) and knee joint replacements.

Solid phase orientation processing of polymers at temperatures above their glass transition point, but below their melting point, provides the major route to imparting a wide range of polymer molecular orientation, from low up to very high levels. This can be utilized to create dynamic devices which change shape in-situ on exposure to temperature or, potentially, body fluid, allowing the device to adapt to the surrounding bone topology. Protype devices will be manufactured from known resorbable or inert polymers, inorganic particles and suitable plasticisers all having known clinical history. The devices will be programmed to mechanically function and then degrade to expose known inorganic salts/scaffolds which can then be used to promote osteogenesis. In the case of medical implants such as tissue fixations, the recovery typically needs to take place at an appropriate temperature to avoid tissue damage (so less than ~50C), or (more challenging) be driven by exposure to body fluids, and to occur in an acceptable timescale to the operating clinicians (e.g. less than 15 s), and to retain fixation strength over required timescales (months for bioresorbables, permanent for non-resorbables).

In addition to the solid phase orientation processing route, a range of melt processing techniques can be used to obtain (in general) lower levels of orientation but which may have other advantages in terms of manufacturing, including net shape processing. Novel variants of these are explored in the Research Programme,including:
(a) micromoulding (single shot property gradient products, or over-moulded products, and surface feature control),
(b) micro-extrusion (for precision preforms for die drawing, or controlled surface continuous products), and
(c) hybrid processing, such as a novel injection-drawing process.

Manufacturing challenges to be addressed include (i) the overall goal of 'Smart Manufacturing', defined here as the effective control of property levels through processing, simultaneous with achieving precision geometry products at economic production rates for shape memory polymers; (ii) materials and additives suitability, combined with processability for the complex requirements for bioresorbable fixations; (iii) formation of starting materials suited to manufacturing routes, and (iv) refined modelling for developed understanding of solid and melt phase processing, vital in developing understanding of the processes and process design.

The UK is generally recognised as having a strength in medical device technology and manufacturing. Our major collaborator, S&N is the largest medical device manufacturer in Europe and is UK-owned and head-quartered. Many of the other large medical device companies maintain manufacturing and/or R&D operations in the UK. Another driver of the UK medical device industry is the large number of SMEs that operate in this field. These companies are R&D oriented and frequently work in emerging areas of technology. The project therefore benefits both established large companies, leading to an immediate commercial impact, and has potential longer term impact on emerging industry through the creation of new product concepts enabled by the manufacturing techniques developed. The work can thus contribute to the success of the UK economy in both the short and longer term, and help to maintain the UKs lead in this strategically important area. The project addresses the key societal challenge of an ageing population as well as the needs of younger, active patients. Less invasive implants can lead to shorter hospital stays and faster rehabilitation, thus reducing pressure on the NHS. The programme addresses the EPSRC challenge theme of Healthcare Technologies, and more specifically the strategic priority areas within that theme of "Novel treatment and therapeutic technologies" (via development of novel SMP materials and implants) and "Design, manufacture and integration of healthcare technologies" (via innovative manufacturing methods).

Our process structuring research for polymer-related materials is at the heart of this proposal for 'smart manufacturing' of medical devices and has had significant impact in fundamental research results through to commercial spin outs, and has achieved high levels of academic and industrial collaboration, and a strong international cooperation platform. The current proposal will build upon these successes - in our university, regionally and nationally, and internationally, all to the clear benefit of the UK. The resourcing will be from a partnership of EPSRC, the University of Bradford, the supply chain in industry, and will also have international academic collaborators, in particular Sichuan University. It will have valuable synergy with the new Centre for Innovative Manufacturing in Medical Devices.

There is clear national and international value in the programme as our programme aims to focus on smart manufacturing (which we define here as the effective control of property levels through processing, simultaneous with achieving precision geometry products at economic production rates) exploiting advanced materials for development of medical device products aligned with strategic priorities of the British government in health delivery policies and associated industries - very much in line with EPSRC priorities in Manufacturing the Future, both in terms of novel, high value-added products from controlled, precision manufacturing routes which exploit our underpinning scientific knowledge, and doing this in a 'resource efficient' manner, by significantly enhancing the properties or functionality of specific polymers, creating significant added-value, and also EPSRC priorities in Healthcare Technologies.
Internationally, our project aligns with UK-China agreed strategic priorities for research collaboration. The international angle is of particular interest for impact, given the global nature of our sector and its supply chains, and the common demography issues related to aging populations. Such visibility attracts new collaborations with high level international companies as well as the excellent collaborations we have with the lead partner in this proposal, Smith & Nephew, so building capacity, and new funding streams, all contributing to increased engagement in research. Outputs will also include high quality journal publications, international conference presentations and joint IP.