Portable sweat rate sensors integrated with air ventilation actuators

A portable sweat rate sensor integrated with a thermo-pneumatic actuator for automatic ventilation has been proposed and experimentally verified its performance. The previous forced ventilation sweat rate sensors using external ventilating devices had the problem of the bulky size with the lack of portability. The previous natural ventilation sweat rate sensors with portable sizes meanwhile required a manual ventilation per each measurement. The total weight of the present portable sweat rate sensor is 6.2% of that of the previous forced ventilation sweat rate sensors. The integrated thermo-pneumatic actuator lifts the humidity measuring chamber above the skin for automatic natural ventilation. The portable sweat rate sensor, having a size of 38 ± 0.5 mm × 41 ± 0.5 mm × 29 ± 0.5 mm with a total weight of 63 ± 1 g, is capable of lifting the humidity chamber 1.91 ± 0.27 mm above the skin in a movement cycle period of 3 min. The portable sweat rate sensor measures the sweat rate with a sensitivity of 0.056 (pF/s)/(g/m2h) and a linearity of 99.1% in a sweat rate range of 3.76-137.68 g/m2h. The portable sweat rate sensor is insensitive to the environmental air flow, and thus demonstrates high potential for mobile human thermoregulatory status monitoring applications, such as human monitoring jackets and cognitive air-conditioning systems based on human sweat.