Fig. 4: Outstanding linearity and sensitivity.

a Influence of nonlinearity on the accuracy of strain sensor test results with pre-strain. b The change of capacitance under four step-by-step stretching (10%, 20%, 30%, 40%) and three stretching cycles with an increment of 5%, respectively. c The small strain caused by gentle breathing can cause a significant change in the capacitance of the sensor. d The capacitance of the sensor at 20% and 40% strain and their enlarged diagrams.