Localized Superficial SAR Values (Non-Compliance Metric) in Scalp Skin at THz Frequency

The Terahertz (THz) Electromagnetic radiation is increasingly relevant for next-generation mobile communication technologies (6G) at THz frequencies, electromagnetic energy absorption is confined to micrometer-thin layers of the skin, making conventional specific absorption rate (SAR) metrics physically inappropriate for compliance assessment. This study presents localized superficial SAR values in human scalp skin under THz mobile handset exposure frequency, clearly designated as a non-compliance metric for interpretive purposes only. The Calculations account for realistic incident electric fields and induced electric field at the air–skin interface and inside scalp. While the superficial SAR values appear high due to normalization over an extremely small tissue volume, corresponding incident power densities and estimated surface temperature rises remain well within internationally recommended safety limits. The results confirm that volumetric SAR is unsuitable for THz exposure assessment, and that surface power density and temperature elevation are the appropriate parameters. No significant energy reaches deeper tissues or the brain, supporting the thermal safety of human scalp under realistic THz handset operation.