Under pressure: The effect of system, surface geometry, and load on the measure of contact pressure

Many human activities involve carrying payloads using a load carriage system, including backpacks, exoskeletons, and utility belts. Poorly designed systems can lead to musculoskeletal injury, pain, and discomfort. The distribution of skin contact pressure is a common biomechanical metric for assessing ergonomic designs that are both safe and comfortable. Although many studies highlighted the technical challenges of early pressure measurement systems, systematic evaluations of modern systems remain limited, despite their growing application in research and industry. This study compared three modern pressure measurement systems for absolute error and drift rate. The Novel Pliance®, Tekscan I-Scan™, and XSENSOR™ X3 systems were calibrated according to the manufacturer's protocol and tested on a flat and curved surface for pressures between 30 and 90 kPa. Ten independent trials were collected per system, surface, and load at 30 min of static pressure. Novel Pliance® exhibited the lowest absolute error (4.51 ± 2.26 kPa) and drift rate (0.05 ± 0.06 kPa/min), which significantly differed from Tekscan I-Scan™ (absolute error: 7.16 ± 4.70 kPa; drift rate: 0.15 ± 0.11 kPa/min) and XSENSOR™ X3 (9.29 ± 4.90 kPa; 0.08 ± 0.07 kPa/min). Moreover, Novel Pliance® exhibited no absolute error difference per surface and load, and drift significantly lessened over time in nearly all conditions. This study presents the importance of pressure measurement system selection in biomechanical research to enhance data accuracy, reduce confounding variables, and improve the validity of ergonomic evaluations.