Background
In daily diabetic foot care, much attention is given to pressure under the foot. However, there is growing awareness that another type of force may also play a role in the development of ulcers: shear forces. These forces act parallel to the skin and may contribute to tissue damage, especially in people with neuropathy who no longer feel pain as a warning signal.
Despite this, shear forces are still not part of routine clinical assessment. One important reason is practical: they are difficult to measure. Existing systems either provide only limited, short-term measurements or lack the detail needed to understand what happens locally under the foot during daily activities. At the same time, ulcer development is a highly local process, which means that precisely this local information is essential.
As a result, part of the mechanical loading of the foot remains insufficiently understood. Onur Okcu, PhD candidate affiliated with the German Sport University Cologne, aims to address that gap by developing a system that can measure shear forces inside the shoe during real-life use.
Approach
The project focuses on the development and validation of a new in-shoe sensor system that can measure shear forces at different locations under the foot. In addition to the sensor itself, software is being developed to calibrate the system, visualise the data in three dimensions, and support interpretation by researchers and healthcare professionals.
The research is carried out in three steps.
First, the sensor is tested under controlled laboratory conditions. This phase examines whether the measurements are accurate and consistent when compared to known reference forces, and how different materials and surfaces influence the results.
Next, the system is tested in healthy participants to better understand how footwear, pressure, and shear forces interact during walking.
Finally, the system is applied in people with diabetes who have previously had a foot ulcer. In this phase, the focus is on how shear forces change when footwear is optimised, and whether these changes follow the same patterns as pressure reduction. This is particularly relevant for clinical practice, where footwear adjustments are a key part of prevention.
From measurement to better prevention
By making shear forces measurable in daily life, this project aims to add a missing piece to our understanding of mechanical stress on the diabetic foot.
For healthcare professionals, this could lead to more informed decisions when assessing risk or optimising footwear. It may help to explain why some ulcers still develop despite adequate pressure reduction, and whether additional adjustments are needed.
Ultimately, the goal is not to replace existing methods, but to complement them. A more complete picture of the forces acting under the foot may support earlier recognition of risk and more targeted prevention strategies, with the aim of reducing the number of foot ulcers and amputations.
Research Team
The project is carried out at Novel GmbH, a company with extensive experience in electronics, sensor technology and software for biomechanical and medical applications. Novel previously developed systems such as emed® and pedar®, which are widely used for measuring pressure distribution under and inside the foot.
The doctoral candidate works with a multidisciplinary team of physicists, engineers and software developers. There is also collaboration within DIALECT with another doctoral candidate who focuses on a different aspect of foot loading, namely horizontal forces.
German Sport University
As part of the project, the doctoral candidate undertakes secondments at the German Sport University Cologne and at Steno Diabetes Center Copenhagen. In Cologne, the focus is on testing materials, sensor performance and prototype hardware and software. In Copenhagen, the focus is on patient behaviour, pilot testing with users, and gaining insight into daily clinical practice in diabetic foot care.
The German Sport University Cologne is an internationally oriented university with strong expertise in sport science and applied research. Within this project, the doctoral candidate is affiliated with the Neuromechanics and Musculoskeletal Biomechanics Group at the Institute of Biomechanics and Orthopaedics.
This group studies how the body adapts to physical loading in both sport and daily life. This knowledge contributes to a better understanding of how foot loading develops over time and how it affects people with diabetes. The German Sports University (GSU) will be the PhD awarding institute for the doctoral candidate. This also means that the doctoral candidate will follow the doctoral program of the GSU. For further information see here.
Doctoral Candidate
Onur Okcu
Recruiting organisation: Novel GmbH, Ismaninger Str. 51, 81675 Munich, Germany
Hosts: Dr. Axel Kalpen; Dipl. Ing. Peter Seitz; Dr. Ahmad Dahrouj
Duration: 36 months
Secondments: GSU, Cologne, Germany (2 months); Istituto Orthopedico Rizzoli, Bologna, Italy (2 months); OIM Voetzorg / Feeture, Amersfoort, Netherlands (1 month).
Summary: The risk of developing a foot ulcer in people with diabetes increases with the presence of loss of protective sensation, biomechanical abnormalities and peripheral vascular disease. In people at high risk of ulceration, we have incomplete understanding of the pathogenesis of ulcer recurrence. Biomechanical factors are important, but there are gaps in our knowledge concerning the extent and mechanisms through which biomechanical factors contribute to ulceration and amputation. One of those gaps is regarding the role of shear in the development of foot ulcers, where general consensus is that this factor plays a significant role, but we are not able to quantify it because a system or sensor that measures shear inside a patient’s shoe is currently not available. In this DIALECT project, we aim to develop the first of its kind sensor that can measures shear inside people’s footwear, to help improve our understanding of the role that shear plays in ulcer development and in evaluating footwear for people with diabetes for shear-reducing capacity.