A psychosocial stress task increases finger mechanical impedance

Stress monitoring during daily work can enable early detection of work-related stress. Conventional stress monitoring requires collecting biological samples or wearing sensors, while existing unobtrusive methods face challenges regarding context. To address the issue, this work focuses on finger joint stiffness as a new stress indicator. We hypothesized that finger joint stiffness increases under stress. To validate this hypothesis, we measured the mechanical impedance of the index finger during baseline rest and stress tasks (speech and mental arithmetic) in an experiment with 15 participants. As a result, the mechanical impedance of the finger during the stress tasks was significantly higher than that at baseline ( $$p < 0.05$$ ). These findings indicate that psychological stress increases finger joint stiffness, suggesting its potential as a stress metric.