Figure 4.

Electromechanical performances of CMCS-Ca²⁺/PAAm/PNMA hydrogels and their strain sensors. (a) Conductivity value as a function of different CaCl₂ addition content; (b) relative resistance change and linear fit of the strain sensors made of CMCS-Ca²⁺/PAAm/PNMA hydrogels as a function of strain; (c,d) plots of ΔR/R₀ vs. time with stretching–relaxation under different strains from 0.5% to 500%. (e) The ΔR/R₀ curves of CMCS-Ca²⁺/PAAm/PNMA hydrogel under the 0% to 500% applied strain at the stretching rate of 100 mm/min. (f) Response and recovery time of the CMCS-Ca²⁺/PAAm/PNMA hydrogel sensors. (g) The resistance response of the CMCS-Ca²⁺/PAAm/PNMA hydrogel sensors over 11,000 stretching–relaxation cycles at 100% strain under 2000 mm/s tensile speed.