Evaluating the dynamic thermal sensitivities of human body with high-dense contacting thermal stimuli

Existing research have explored thermal sensitivity under steady thermal conditions while how it changes with time is unknown. In this study, the arm and face were taken as examples to study dynamic characteristics of thermal sensitivity. The test spots were stimulated under thermally neutral ambient conditions to obtain skin temperature and thermal sensation at three levels (e.g. the micro-scale (1.54 cm2) spot, local body part and whole body) at intervals of 4 s. Results showed that in the first 4 s of stimuli, skin temperature change would reach 52% of the final variation. The overshooting rate of the arm thermal sensitivity was 1.6 and 1.8 times over the stable state for cooling and heating stimuli, and that of the face was 1.9 and 2.0 times. 95% of subjects on the arm and 85% on the face were more sensitive to cooling stimuli. The warmth sensitivities of different genders and body parts were shown to be significantly different, while the cold sensitivity of different body parts produced small differences. When stimulating one test spot, the ratio of thermal sensation at three levels was 15:4:1 on the arm and 16:3:1 on the face. These results can help to understand how the body responds to spatially ununiform and temporally unsteady thermal exposures.