Design of a Flexible Ultra-Thin Wearable Frostbite High-Precision Warning System

This paper presents a flexible, ultra-thin, highprecision wearable system for early-stage frostbite detection in extreme cold environments. The system is built on the ESP32S3 microcontroller. A two-stage digital filtering algorithm ensures measurement stability under motion and external interference, achieving an average absolute error of ± 0.08 °C. The circuit employs a flexible printed circuit made from 0.1 mm copper foil, offering high mechanical durability and enhanced wear resistance in harsh environments. Furthermore, the decoupled design, comprising a sensor unit (10×20 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>) and a processor unit (25×20 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>), enhances wearability and enables modular, multi-point deployment. By utilising Bluetooth Low Energy (BLE) based on the Message Queuing Telemetry Transport (MQTT) protocol, the system enables secure, lowlatency, real-time data transmission with both cloud and mobile interfaces. The system is well-suited for integration into gloves, insoles, and cold-weather gear, offering practical applications in occupational safety, military operations, and outdoor expeditions.