The remote sensing of mental stress from the electromagnetic reflection coefficient of human skin in the sub-THz range

• Published in: Bioelectromagnetics Vol. 33; no. 5; pp. 375 - 382
• Main Authors: Safrai, Eli, Ishai, Paul Ben, Caduff, Andreas, Puzenko, Alexander, Polsman, Alexander, Agranat, Aharon J., Feldman, Yuri
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-07-2012
• Subjects: Adult; antennas; Blood Pressure - radiation effects; Color; Electromagnetic Phenomena; epidermis; Female; Galvanic Skin Response - radiation effects; Heart Rate - radiation effects; human skin; Humans; Male; mental stress; Reaction Time - radiation effects; reflection coefficient; Skin - physiopathology; Skin - radiation effects; Stress, Physiological - radiation effects; Stress, Psychological - physiopathology; Stroop effect; sweat ducts
• ISSN: 0197-8462; 1521-186X
• DOI: 10.1002/bem.21698

Recent work has demonstrated that the reflection coefficient of human skin in the frequency range from 95 to 110 GHz (W band) mirrors the temporal relaxation of stress induced by physical exercise. In this work, we extend these findings to show that in the event of a subtle trigger to stress, such as mental activity, a similar picture of response emerges. Furthermore, the findings are extended to cover not only the W band (75–110 GHz), but also the frequency band from 110 to 170 GHz (D band). We demonstrate that mental stress, induced by the Stroop effect and recorded by the galvanic skin response (GSR), can be correlated to the reflection coefficient in the aforementioned frequency bands. Intriguingly, a light physical stress caused by repeated hand gripping clearly showed an elevated stress level in the GSR signal, but was largely unnoted in the reflection coefficient in the D band. The implication of this observation requires further validation. Bioelectromagnetics 33:375–382, 2012. © 2011 Wiley Periodicals, Inc.