Fig. 3: Stability of the SEMS and the influence of sweat on pulse and touch detection.

a, b Photographs of (a) the CE (counter electrode) and (b) SE (sensing electrode) under stretching (~10%). Scale bar: 2 cm. c Responses by touching the SE and CE. No output was found when touching the CE. d Signal stability over 5000 loading/unloading cycles at a peak pressure of 5 kPa. The picture on the top shows the details of 50 cycles (from the 4800th to the 4849th cycle). e, f Skin conditions after 24 h of attachment of the sensing electrode e with and f without a spacer. No skin irritation in the electrode area was observed during the attachment. Scale bar: 2 cm. g Recorded capacitance of the SEMS during the test from a human subject who performed 10 min of exercise and back to rest state for 40 min. The insets showed the optical photos of fingertip with sweat and no sweat. Scale bar: 0.5 mm. h The amplitudes of pulse waves at different points of 0, 12, 14, 16, 20, 30, 40, and 50 min. n = 10 consecutive measurements, each one represents value of amplitude of pulse wave. Data are presented as the mean values±standard deviations: 1.06\(\pm\)0.07, 1.13\(\pm\)0.06, 0.85\(\pm\)0.06, 0.84\(\pm\)0.05, 0.86\(\pm\)0.05, 1.04\(\pm\)0.04, 0.85\(\pm\)0.09, and 0.99\(\pm\)0.05 pF. The variation of pulse rates from 0 to 50 min is shown at the bottom. i The responses to touches before sweating and with sweating.