Fig. 1.
a The experimental setup. b An example of two-dimensional laser speckle measurements of skin blood flow in seven different facial regions [right (1) and left (2) infraorbital, right (3) and left (4) cheek, subnasal (5), lips (6), and chin (7)]. c Baseline facial skin blood flow is compared among the facial regions (n = 12 subjects). Skin blood flow in the lips was the highest. AU arbitrary unit