智慧醫療腋溫連續監測系統之設計

Abstract

中文摘要 本研究旨在設計一套智慧醫療腋溫連續監測系統，以穿戴式貼片作為系統應用形式，改善傳統電子體溫計僅能進行單次量測、不易長時間追蹤人體體溫變化的限制。系統主要針對人體腋下約 35°C～42°C 的溫度範圍進行量測，期望應用於居家照護、病房監測及發燒追蹤等情境。在系統設計上，選用 Pt1000 白金電阻式溫度感測器，利用其良好的線性度、穩定性及重複性進行溫度感測，並採用 100 μA 定電流法將感測器的電阻變化轉換為電壓訊號。系統搭配 2.5 V 精密參考電壓及 OPA333 精密運算放大器進行訊號緩衝與放大，再由 ESP32 的 ADC 讀取訊號並換算為體溫。為提升量測穩定性，系統亦規劃 RC 低通濾波、電源去耦合及移動平均濾波等雜訊抑制方法，並透過 OLED、LED 與手機 APP 提供體溫顯示及發燒警示功能。經電路設計與理論計算，在 35°C～42°C 範圍內，Pt1000 電阻約由 1134.75 Ω變化至 1161.7 Ω；以 100 μA 定電流驅動時，感測器輸出約為 113.475 mV～116.17 mV，電壓變化量約 2.695 mV，因此後級設計約 500 倍放大倍率，並加入基準電壓偏移，使輸出落於 ADC 可讀取範圍。整體設計可作為穿戴式連續腋溫監測系統之基礎架構，並提供後續實作、校正與量測驗證使用。

Abstract This study aims to design a smart healthcare system for continuous axillary temperature monitoring using a wearable patch. The system is intended to overcome the limitation of conventional electronic thermometers, which are mainly designed for single measurements and are not suitable for long-term continuous monitoring. The target measurement range is approximately 35°C to 42°C, making the system suitable for home healthcare, hospital monitoring, and fever tracking. A Pt1000 platinum resistance temperature detector is selected as the temperature sensor because of its good linearity, stability, and repeatability. A constant current of 100 μA is applied to convert the resistance variation of the Pt1000 into a voltage signal. A 2.5 V precision reference voltage and an OPA333 precision operational amplifier are used for signal buffering and amplification. The processed signal is then acquired by the ADC of an ESP32 and converted into temperature data. To improve measurement stability, RC low-pass filtering, power-supply decoupling, and moving-average filtering are also incorporated. An OLED display, LED indicators, and a smartphone application are used to provide real-time temperature information and fever alerts. According to the circuit design and theoretical calculations, the resistance of the Pt1000 varies from approximately 1134.75 Ω to 1161.7 Ω within the range of 35°C to 42°C. With a 100 μA constant current, the corresponding output voltage ranges from approximately 113.475 mV to 116.17 mV, resulting in a voltage variation of about 2.695 mV. Therefore, an amplification stage with a gain of approximately 500 is designed, together with a reference voltage offset, to adjust the output signal to a suitable range for ADC acquisition. The proposed design provides a fundamental architecture for a wearable continuous axillary temperature monitoring system and can serve as a basis for further implementation, calibration, and experimental verification.