Enhanced sensing performance of flexible strain sensors prepared from biaxially stretched carbon nanotubes/polydimethylsiloxane nanocomposites

Flexible strain sensors from biaxially stretched carbon nanotubes (CNTs)/polydimethylsiloxane (PDMS) nanocomposites are fabricated in this study. It is shown that biaxial stretching promotes the homogeneous distribution and alignment of CNTs in the stretching plane, improving the sensing performance of the strain sensors. The optimized stretching ratios (SRs) of CNT/PDMS nanocomposites are determined. Compared to an unstretched CNT/PDMS-1.0 sensor (gauge factor [GF] value = 0.73, detectable range from 0 to 60%), the 1.5 wt% CNT/PDMS-1.5 sensor (SR = 1.5) exhibits enhanced strain sensitivity (GF = 2.8), a wider detectable range (0-370%) and better performance stability. The GF values of CNT/PDMS-2.0 and CNT/PDMS-2.5 sensors with SRs of 2.0 and 2.5, respectively, were 1.18 and 1.06, respectively, due to more significant conductive network reconstruction in the process of applying strain, leading to a decreasing GF. The possibility of sensors in the application of wearable electronic components is also demonstrated. The sensor shows a clear and stable signal output when different strain modes are applied, such as tensile, compressive, bending, and twisting.