Mat-Based Foot Temperature Monitoring Device for Early Detection of Diabetic Foot Ulcers

Abstract Diabetic foot ulcers (DFUs) are a serious complication of diabetes, and their early detection is key to prevention. Diabetes alters plantar soft tissue biomechanics by increasing mechanical loading, which can lead to ulcers. Along with the traditional screening methods, plantar pressure and temperature are the parameters to predict and understand DFU in adults. In this study, a plantar temperature mat comprising 32 thermistors embedded in ethylene-vinyl acetate (EVA) (16 per foot) is developed, combined with external analog-to-digital converters (ADCs) and two ESP32 microcontrollers. The data were transmitted wirelessly to a PC for visualization and storage. The prototype was evaluated in a gait laboratory on 13 participants (ten healthy, three diabetic) using a published treadmill protocol. Device and handheld infrared (IR) temperatures were recorded at five plantar sites on both feet before and after activity, yielding 260 paired measurements. The pooled device–IR bias was 1.75 °C (SD 1.56 °C) and 1.44 °C after excluding one influential diabetic participant. Contralateral regional differences in healthy subjects remained below the 2.2 °C clinical threshold. Regional peak plantar pressure correlated moderately with local temperature (r ≈ 0.35–0.39, p < 0.001). Temperature rise versus estimated energy expenditure showed a positive but nonsignificant trend (pooled slope ≈ 0.14 °C kcal−1; r ≈ 0.40, p ≈ 0.20). In diabetic patients (n = 3), seven single-session exceedances of the 2.2 °C threshold were observed (7/60 = 11.7%; 95% confidence interval, Wilson 5.8–22.2%). The prototype shows promise for cost-effective DFU screening and can be utilized in a professional healthcare environment.