Fig. 3: Basic sensing behaviors of the sensor.

a Relative resistance changes versus strain. b The electrical impedances of HTF–CGF samples in the 0–30% strain range. c Relative resistance changes under various strain rates. d Response time under 0.3% strain loading/unloading. e Dynamic responses under different strains. Inset: responses under a slight strain of 0.1%. f Cyclic repeatability test