Figure 2
From: Evaluation of mental stress by physiological indices derived from finger plethysmography
Finger plethysmography. (A) Pressure-controlled cuff with reflective sensor plate in finger plethysmography. Air pressure in the airbag at the top is adjusted by a pressure-controlled pulse wave recorder so that the fingertip is held lightly in place. The reflective sensor below the finger detects the finger pulse wave from the surface of the skin. The stop block acts as a guide to keep the finger in the correct position. (B) Schematic of measurement and analysis systems of finger plethysmography. FPG, finger plethysmograph; PC, personal computer.