We have developed a calorimetric sensor that can perform local measurements of the heat flux transmitted by conduction between a human body and thermostat located inside the sensor. The sensor has a detection area of 2 × 2 cm2 and, in its current configuration, facilitates measurement with a resolution of 10 mW. In this paper, measurements of two healthy male subjects of different ages (24 and 60 years) are presented. We study the variation in the power dissipated by the human body surface as a function of time for a thermostat temperature of 28 °C. We also study the same power with thermostat temperatures varying from 24° to 36°C. Measurements are performed on three different surface areas of the human body: the sternum, abdomen, and hand. The ambient room temperature during all measurements was in the range of 22-24 °C, and the subjects were seated and resting. The results show that the heat flux in the trunk is much more stable than that in the hand and that the heat flux in the sternum is greater than that in other areas. Additionally, this flux is higher in the younger subject (42 mW/cm2) than in the older subject (35 mW/cm2). We also defined a thermal parameter that represents the thermal resistance between the sensor thermostat and the skin. The mean value of this parameter varies between 51 and 71 K/W depending on the subject and measurement area.
Keywords: Direct calorimetry; Heat conduction calorimeters; Isothermal calorimeters, Medical calorimetry; Non-differential calorimeters; Physiology.
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