Fig. 5: AFM force-relaxation schematic diagram and typical data for corneocytes.

a Schematic diagram of the stress-relaxation measurement consisting of an approach curve, a pause segment, and a retraction curve. The measurements were performed on cells fixed on a glass slide. b Representative force as a function of time data consisting of three stages: (I) loading curve up to a maximum force setpoint of 2 µN, followed by (II) a 4 s pause at a constant vertical AFM head height (Z height) and, finally, (III) the retraction of the probe from the cell surface. c The force-relaxation curve was fitted by a Prony series to obtain the time-dependent mechanical properties of corneocytes.