We propose watch-type sweat rate sensors capable of automatic natural ventilation by integrating miniaturized thermo-pneumatic actuators, and experimentally verify their performances and applicability. Previous sensors using natural ventilation require manual ventilation process or high-power bulky thermo-pneumatic actuators to lift sweat rate detection chambers above skin for continuous measurement. The proposed watch-type sweat rate sensors reduce operation power by minimizing expansion fluid volume to 0.4 ml through heat circuit modeling. The proposed sensors reduce operation power to 12.8% and weight to 47.6% compared to previous portable sensors, operating for 4 hours at 6 V batteries. Human experiment for thermal comfort monitoring is performed by using the proposed sensors having sensitivity of 0.039 (pF/s)/(g/m²h) and linearity of 97.9% in human sweat rate range. Average sweat rate difference for each thermal status measured in three subjects shows (32.06 ± 27.19) g/m²h in thermal statuses including 'comfortable', 'slightly warm', 'warm', and 'hot'. The proposed sensors thereby can discriminate and compare four stages of thermal status. Sweat rate measurement error of the proposed sensors is less than 10% under air velocity of 1.5 m/s corresponding to human walking speed. The proposed sensors are applicable for wearable and portable use, having potentials for daily thermal comfort monitoring applications.

中文翻译：

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用于人体热舒适性监测的可穿戴汗水率传感器。

我们提出了通过集成微型热气致动器实现自动自然通风的手表式汗水速率传感器，并通过实验验证了它们的性能和适用性。以前使用自然通风的传感器需要手动通风过程或大功率笨重的热气致动器，以将出汗率检测腔提升到皮肤上方以进行连续测量。拟议中的手表式汗液速率传感器通过热回路建模将膨胀液量降至0.4 ml，从而降低了操作功率。与以前的便携式传感器相比，拟议的传感器在6 V电池下可工作4小时，从而将其工作功率降低至12.8％，并将重量降低至47.6％。使用建议的灵敏度为0.039（pF / s）/（g / m ²h）在人类出汗率范围内线性度为97.9％。在三名受试者中测得的每种热状态的平均出汗率差异显示（32.06±27.19）g / m ² h，包括“舒适”，“略热”，“温暖”和“热”的热状态。因此，所提出的传感器可以区分和比较热状态的四个阶段。在与人类步行速度相对应的1.5 m / s的风速下，提出的传感器的出汗率测量误差小于10％。拟议的传感器适用于可穿戴和便携式用途，具有日常热舒适性监测应用的潜力。