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    In this blog, University of Sheffield based researcher Dr Nicholas Farr explains why investing in the development of testing methods is key to ensuring medical devices are safe to use. His current work focuses on how the materials used in medical devices react within the body. Most recently, he has looked at mesh implants and how they degrade and change over time.

    Nicholas and colleagues at the University of Sheffield have developed innovative testing methods that mimic key features of the human body within the lab. He believes this will improve our understanding of the materials being used in the development of medical devices at an early stage in the process – saving time and money, and reducing the risk of patient harm. 


    Bringing a medical device to market

    NTHFSorby.thumb.jpg.77f94526c34fe3f401445bda6ec91036.jpgHere in the UK*, medical devices are regulated by The Medicines and Healthcare products Regulatory Agency (MHRA). The MHRA is responsible for ensuring the quality and safety of medical devices by enforcing UK legislation and working with manufacturers.

    The MHRA offers guidelines and guidance to help manufacturers transition from lab-based experiments to animal studies, and lastly through to clinical trials (in human). Once these stages are complete, they evaluate the assessments and trials undertaken together with their results and decide whether to approve or deny certification.

    Before any costly animal or human trials take place, manufacturers will conduct tests on the medical device in a lab. These test methods are prescribed by international standards (eg ISO) that are produced by experts within a particular field. The aim is to provide a best practice guide.

    Knowledge gaps hinder progress

    From my experience, it seems a lack of understanding of how materials interact within the body is impeding the development of medical devices and having a detrimental effect on patient safety.

    Of the 309 medical devices registered for a CE mark between 2005 and 2010, nearly 25% were recalled or had a safety alert by the start of 2016.[1] Despite the UK life sciences industry experiencing a turnover of £88.9 billion in 2020, lack of successful translation from lab to clinic is commonplace with a pharmaceutical clinical trial failure rate of 90%.[2]

    Better testing essential for safetyNTHFHistology.thumb.jpg.ec48a9710188f3e4fe3f581a4fb21992.jpg

    At this stage it is clear to me that the development of more effective and comprehensive test methods, which can be applied in the lab, would greatly reduce the amount of current animal testing and improve the safety of medical devices developed in the future.

    This was raised by the `First Do No Harm` UK Government report:

    Innovation without comprehensive pre-market testing… is, quite simply, dangerous.”[3]

    My research has focused on the development of methods which can better test medical devices before they start animal trials. My methods involve exposing a medical device to both mechanical stress and oxidative stress, both of which are known to occur within the body.[4,5]

    During and after this stress application, I use techniques to image and evaluate the effects on the surface of the material.[6] Essentially, our simple lab-based testing methods are improving our understanding of how a device or material might behave if it were implanted inside a human body, and the safety implications that go with this.

    To date no Standards have adopted an approach which allows for this form of analysis.  

    Far-reaching benefits

    The information gained from testing materials with more effective methods can be used to influence and aid the future development of medical devices – learning from our past mistakes and reducing the risk of patient harm.

    Ultimately, it is in everyone’s interest to develop new life-altering and life-saving materials that can be safely used in medical devices.

    Supporting manufacturers to deliver safe devices

    In practice medical devices are developed through the efforts of commercial manufacturers. I am confident that the approach to medical device material development that we are advocating will not only provide an improved outcome for patients but also has the potential to reduce costs and ‘time to market’ for the manufacturers.

    Currently we seem to be in a situation where the focus is to understand why a device has failed rather than reduce the likelihood of failure during development. We’d like to help change this and are very open to manufacturers who wish to engage with our research.

    Final thoughts

    I suppose that it does sound rather like a cliche but as a researcher I am motivated by the quest for knowledge and, perhaps even more importantly, the beneficial exploitation of that knowledge. 

    If our work in Sheffield can result in lower manufacturing costs, improved medical devices and better outcomes for patients, I will be a happy man. 

    If you are interested in our work, you can get in touch with me at n.t.farr@sheffield.ac.uk


    * Following the UK’s withdrawal from the European Union (EU), the shared EU legislation on Medical devices was continued and given effect in UK law. This means the Medical Devices produced in the UK or EU are required to follow requirements set out in EU legislation. Other countries, such as USA, China and Australia use their own regulatory bodies and legislation to approve the sale of medical devices in their countries. However, the expectation is that developers follow internationally recognised standards in the development of their devices.


    1. Hwang TJ, et al. Comparison of rates of safety issues and reporting of trial outcomes for medical devices approved in the European Union and United States: cohort study. doi:10.1136/bmj.i3323.
    2. Mullard, A. Parsing clinical success rates. Nat Rev Drug Discov 15, 447 (2016). https://doi.org/10.1038/nrd.2016.136
    3. The IMMDS Review, First Do No Harm: The report of the Independent Medicines and Medical Devices Safety Review, 8 July 2020.
    4. Farr NTH, Roman S, Schäfer J, Quade A, Lester D, Hearnden V, MacNeil S & Rodenburg C (2021) A novel characterisation approach to reveal the mechano–chemical effects of oxidation and dynamic distension on polypropylene surgical meshRSC Advances, 11(55), 34710-34723. 
    5. Farr NTH, Rauert C, Knight AJ, Tartakovskii AI & Thomas KV (2023) Characterization and quantification of oxidative stress induced particle debris from polypropylene surgical meshNano Select.
    6. Farr NTH, Klosterhalfen B & Noé GK (2023) Characterization in respect to degradation of titanium‐coated polypropylene surgical mesh explanted from humansJournal of Biomedical Materials Research Part B: Applied Biomaterials

    Are you a researcher looking to share your work?

    If you are a researcher with insights to share around patient safety in health or social care, you can get in touch with us at content@pslhub.org

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