Sensitivity optimisation of an optical pressure sensor-based low-cost dynamic pedograph for improved foot pressure analysis

Accurate measurement and analysis of dynamic foot pressure are crucial for preventing complications associated with peripheral neuropathy, particularly in individuals with diabetes. This study focuses on optimising the calibration and sensitivity of an optical pressure sensor-based dynamic pedograph, designed and made in Bangladesh, to enhance its accuracy in assessing foot pressure distribution. The system employs total internal reflection in a transparent glass slab; foot-applied pressure disrupts light propagation, producing scattered light that is captured as greyscale intensity by a camera positioned beneath. Calibration was performed using a custom four-pad platform, establishing a linear relationship between applied pressure and pixel intensity (100-200 out of 255). Dedicated Java-based software enabled real-time analysis and precise correlation. Systematic tuning of camera parameters - gamma 100, gain 0, contrast 0 - enhanced sensitivity, linearity, and spatial uniformity, with spatial sensitivity variation of 8.2% and temporal variation of 1.92, indicating stable performance. The optimised pedograph generates high-resolution pressure maps, providing a cost-effective, reliable alternative to commercial systems, supporting improved plantar pressure assessment and diabetic foot care in clinical settings.