Personalized Skin Temperature Benchmark via Wireless Wearable Sensor for Assessing Peripheral Thermoregulation

Hypothermia constitutes a substantial risk in outdoor and occupational environments. However, conventional assessment methods rely on population‑based statistical norms, which often fail to account for interindividual variability. This study proposes the concept of a personalized skin temperature benchmark, defined as an individual‐specific database of skin temperature acquired from multiple body sites and associated with health status as well as environmental conditions. To realize this concept, a custom‑designed wireless wearable flexible temperature sensor was developed, enabling comfortable and continuous monitoring at the wrist, forehead, and chest. Data were collected from two healthy male subjects by systematically varying physical activity level and clothing insulation index, while simultaneously measuring apparent temperature (which depends on ambient temperature, humidity, and wind speed). The results revealed significant differences in skin temperature benchmarks between the two individuals. A key parameter (skin heat loss) is introduced to quantify peripheral thermoregulation, with its values serving as a personalized indicator, and peripheral thermoregulation classification requires further validation. A critical step toward non‑invasive early warning of hypothermia lies in establishing reliable skin–core temperature calibration, yet this remains an open challenge.