Tribology is everywhere. It shapes how we design, test, build, and interact with materials and systems across industries. From healthcare to energy, transport to consumer products, tribology connects surfaces with function and people with outcomes.

Surface Interactions is where surface science meets real-world impact. This new Q&A series from PCS Instruments features the people using tribology to tackle real problems - in labs, clinics, and industries around the world.

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We’re opening the series with Dr Sarah Crossland, whose work brings biotribology into focus through the lens of medical engineering. Her research spans diabetic foot care, soft tissue biomechanics, and even menstrual product design. With a background in prosthetics, orthotics, and physical sciences, she brings a clinical perspective to the development of tools like STAMPS (Strain Analysis and Mapping of the Plantar Surface), helping us better understand the pressures and strains that lead to tissue breakdown.

In this Q&A, Sarah shares what drew her into the field, the challenges she’s working to address, and where she sees biotribology making the greatest impact next.

1. What first got you interested in biotribology and diabetic foot care?

I’ve had a winding career that included training in prosthetics and orthotics. Orthotists engineer solutions to provide support for the body with a range of neuro, muscular or skeletal system problems. As an Orthotist I was able to work within the Diabetic Limb Salvage Service at Leeds Teaching Hospitals Trust, where I treated patients who were living with diabetic foot ulceration and discussed with them the problems they faced. This spurred my interest further into understanding more about ulcer formation in diabetes to work towards improved treatment options.

In this field I’ve been able to witness a wide range of medical devices across differing conditions and coupled with a physical sciences background, this formed my general interest in understanding interactions between medical devices and the human body.

2. You developed the STAMPS method (Strain Analysis and Mapping of the Plantar Surface) to measure pressure and strain in shoes. How is it helping us better understand tissue breakdown?

At present the only validated clinically used tools for assessing plantar foot interaction focus on pressure alone. We know shear strain is present in this interaction, but we just aren’t measuring it. If we can’t measure it, we don’t know what impact it is having on the formation of ulcers alongside pressure. By understanding what is happening at this surface better we can better replicate, test, model and predict what changes in the strain combined with pressure will increase or decrease ulceration risk moving forwards.

3. Wearable sensors are playing a bigger role in research. How do you see them shaping testing or medical device design in future?

There is no getting away from the wealth of useful data wearable sensors can provide us with. Wearable data is a key source to improve design of ex-vivo studies for instance. It is also playing a large part in computational models for ‘digital twin’ approaches to healthcare too.

But like all good things, wearables have their own pitfalls. Some of the key issues in this area fall around miniaturisation, device failure, vast data sets and costs that prohibit use. Moving forward in medical device design we also need to be thinking about increasing accessibility to healthcare technologies, and wearables often become an exclusionary factor. In this space, the use of basic imaging analysis is coming to the fore to allow for lower cost approaches to determining properties like strain to improve accessibility. One area wearables is really helping is through improved mapping of in-vivo responses under specific conditions to allow us to better understand and implement these within benchtop studies. Honing in on these outputs and allowing us to better replicate that environment in our research.

4. Standardising soft tissue testing is still a challenge. What would help make it more consistent or reliable?

Improved approaches to stabilising and tensioning the sample to represent in-vivo behaviour would be advantageous. Due to the variability in sample characteristics this presents some key challenges to ensure this can be consistently applied across any soft tissue used.

5. What areas of biotribology do you feel are still underexplored?

The fantastic thing about biotribology is there are still many areas that are underexplored, which is really exciting for me. An area I’m particularly passionate about is feminine hygiene products and their comfort. With such a large global user group requiring these products regularly and a shift in some markets to reusable products that were previously dependent on disposable products, better understanding what can improve comfort is key.

6. What are you most excited about in your work right now?

Tribology is often overlooked in non-obviously aligned industries, but it has a key role to play as we know in a range of environments. One thing I am really enjoying at the moment is working with biomedical industries and looking at unlocking the potential impact that better understanding of tribological interactions could have for their products.

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That's a wrap!

Whether it’s helping improve outcomes for diabetic patients or rethinking how comfort is measured in everyday products, Sarah’s work pushes biotribology into spaces that matter. Her focus on practical tools, user experience, and accessibility is a reminder that tribology isn’t just about surfaces, it’s about people.

To hear more about Sarah’s journey into the field and her clinical perspective on tribology, you can also catch her episode of TribologyTalks here:

🎧 Listen here

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