Fig. 2. Mechanical properties and strain-insensitive conductance of LM sheath-core microfibers.
(A) Tensile stress-strain curves of LM sheath-core microfibers and the hysteresis loops measured at increasing strains (stretching rate: 20 mm/min). (B) Cyclic loading-unloading curves at a fixed strain of 100% for 100 cycles (stretching rate: 20 mm/min; waiting time: 10 min). (C) Resistance changes of the stretch-induced conductivity activation of microfiber after freezing treatment. (D) Strain-dependent resistance changing rate of LM sheath-core microfibers with six different fluoroelastomer loadings [CPVDF-HFP-TFE = 0 (pure LM), 3, 5, 7, 9, and 11 wt %]. (E) Histogram of resistance change rates at fixed strains of different microfibers. (F) Comparison of the maximum strain, initial conductivity, and resistance change rate at 200% strain of LM sheath-core microfiber with other reported strain-insensitive and LM-based stretchable fiber conductors. (G) Resistance changes of the LM sheath-core microfiber over 600 cycles between 0 and 100% strain. (H to J) Resistance changes of the microfiber upon pressing, twisting, and bending.