Abstract

Abstract Summary

Overview

The widespread application of 28 GHz millimeter-wave technology, particularly in fifth-generation wireless communication systems, prompts an investigation into its thermal effects. These can potentially cause pain and damage to human tissues exposed to millimeter waves.

Objective and Methodology

This study identifies the thermal sensation threshold and evaluates its reliability. A focus group of twenty healthy adults was exposed to varying power levels of 28 GHz millimeter-wave radiation on their left middle fingertip. The exposures were administered in controlled conditions at distinct antenna input powers ranging from 0.2 to 3.4 W, corresponding to incident power densities between 27 mW/cm² and 399 mW/cm². Two measurement sessions were conducted on the same day to test the reliability of the thermal threshold sensation using the intraclass correlation coefficient (ICC) and Bland–Altman analysis.

Findings

• The mean thermal sensation thresholds varied from 0.9°C to 1.0°C under conditions of 126 to 399 mW/cm², with a significantly lower threshold of 0.2°C observed at 27 mW/cm².
• Reliability measurements via ICC showed poor to substantial values depending on the exposure level, with higher reliability at higher exposure levels.
• All participants experienced thermal sensations at the highest exposure level (399 mW/cm²), but the perception rate decreased at lower levels, indicating an inherently ambiguous nature of thermal sensation perception among humans.

Conclusion

The study suggests that a consistent thermal sensation threshold is approximately 1.0°C across different exposure levels. Furthermore, while the threshold’s reliability improves with increased exposure, the perception of thermal sensation remains subjective, highlighting the complexity of human sensory perception.