Mapping the influence of spatiotemporal distribution of skin contact temperature on perceived thermal sensation in human fingers

The temperature distribution upon direct skin contact with a hot solid surface plays a critical role in the resulting human physiological response as it influences both thermal sensation and pain perception. This study aims to advance understanding regarding the skin contact temperature (T_SC) and its spatial distribution on the skin surface upon direct contact with a hot solid surface maintained at a fixed temperature (T_H) ranging from 50 to 70 °C, using an innovative visualization technique under controlled thermal conditions with human subjects. Results highlight significant gender-based differences in changes in the spatial summation of T_SC, with male subjects exhibit an average of 4.2 °C higher than that of female subjects at elevated T_H levels, while females adapt faster, resulting in longer pain onset times. Additionally, this study explores the effects of skin properties, specifically skin thickness and skin viscoelasticity, on changes in the spatial summation temperature (delta T_SC,S) and thermal sensitivity; the findings demonstrate limited influence at moderate T_H, with marginal effects at higher T_H. These insights have significant implications for the design and development of safer prosthetics, thermal devices, and haptic technologies. By establishing guidelines such as maintaining the delta T_SC,S value below 10 °C to mitigate pain onset, this research provides critical parameters for creating systems that accurately mimic human physiological responses to thermal input. Future studies should explore these thermal psychophysical responses across diverse populations and dynamic conditions to broaden the applicability of the insights gained by the present work.