Strong linear-piezoresistive-response of carbon nanostructures reinforced hyperelastic polymer nanocomposites

Here, we report highly strain-tolerant and sensitive strain sensors based on carbon nanostructures (CNS)-poly-dimethylsiloxane (PDMS) nanocomposites. CNS consist of clusters of aligned multiwall carbon-nanotubes (MWCNT) with high degree of entanglement and wall sharing between nanotubes. The unique features of CNS result in nanocomposites with very low electrical percolation threshold (0.05 wt% CNS), strong linear-piezoresistive-response up to 110% strain, and high sensitivity with gauge factor ranging from 8 to 47. We also present a simple analytical model for predicting resistivity evolution as a function of stretch considering incompressible hyperelastic behavior of CNS/PDMS nanocomposites. CNS/PDMS nanocomposites also show good hysteresis performance and stability up to 100 repetitive stretch/release cycles for 30% maximum strain. Tunable sensitivity and linear piezoresistivity coupled with high stretchability of CNS/PDMS nanocomposites demonstrated here suggest their potential for applications in wearable health and fitness monitoring devices.