Strain sensing behaviors of stretchable conductive polymer composites loaded with different dimensional conductive fillers

Herein, we investigate the dependence of the strain sensing behaviors of isoprene rubber (IR) based conductive composites on filler dimensionality. It is found that carbon black (CB)/IR composites display ultrahigh strain sensitivity and good recoverability since CB-networks are easily broken under stretching and fast rebuilt under releasing. However, the drawback of CB/IR composites is the high electrical percolation threshold (8.01 phr), leading to the complex processing, poor mechanical properties, and high cost. In contrast, carbon nanotubes (CNTs)/IR composites possess low percolation threshold (1.44 phr) but also low sensitivity and poor recoverability because CNT-networks are more stable under strain. Interestingly, it is observed that combining zero-dimensional CB and one-dimensional CNTs to construct the hybrid CNT-CB networks is an effective route to overcome the drawbacks of CB-networks and CNT-networks, which endows the stretchable CNTs/CB/IR composites with low percolation threshold, high strain sensitivity and good recoverability. Moreover, the demonstration experiments show that the stretchable CNTs/CB/IR composites could be used to detect human motions and emotional expressions. This study provides a deeper understanding of the strain sensing behaviors of the stretchable conductive polymer composites loaded with different dimensional conductive fillers, which helps to design strain sensing materials.