Influencing mechanism on sensitivity of carbonized fabric strain sensors and modification of bridge-connection model: Comparison of three silk woven structures

Abstract

Given the great potential of carbonized fabric strain sensors in wearable devices, carbonized silk fabrics (CSF) with three characteristic woven structures including georgette (CSF-g), crepe de chine (CSF-c) and crepe satin plain (CSF-p) were employed to investigate the dependence of gauge factor (GF) on two critical parameters: initial resistance (R0) and resistance change (ΔR). The results showed that increasing carbonization temperature can effectively reduce R0 and increase GF of CSF-g, but has little effect on CSF-c and CSF-p. It was further found that the GF of both CSF-c and CSF-p were dominated by ΔR related to the crack propagation path, i.e. high sensitivity CSF was typically accompanied by dense “islands” and fine gaps, while low sensitivity CSF was accompanied by wide cracks and sparse “islands”. Accordingly, a modified bridge connection model was proposed to elucidate the relationship between crack morphology and resistance variation. This model successfully achieved continuous exponential fitting of resistance with admirable fitting goodness. Finally, the prepared sensor exhibited an ultra-high GF (916.5) and was well applied in health monitoring and thermal treatment. These efforts put forward guidance to the design and fabrication of ultrasensitive CSF strain sensors.