Highly stretchable and sensitive strain sensor based on polypyrrole coated bacterial cellulose fibrous network for human motion detection

Abstract

Recently, wearable strain sensors based on elastomeric conductive composites have attracted tremendous attention in human motions and physical signals detection. However, it is still challenging to achieve good conjunction between broad strain range and high sensitivity performance for a wide range of applications. Here, we construct a highly stretchable and sensitive natural rubber (NR) based strain sensor from polypyrrole modified bacterial cellulose nanofiber (cPPy/BCNF) network. Due to the large aspect ratio and strong interfacial interaction of BCNF templates, cPPy/BCNF could form continuous conductive pathways in NR matrix with an extremely low loading, thus greatly reducing the permeability threshold of the elastomer. Consequently, our strain sensor performs remarkable sensitivity over a broad strain range (0–388%) and long-term reliability (3000 cycles at 60% and 180% strain). Particularly, a high gauge factor of 355.3 recorded in the strain range of 279–388% has been achieved, outperforming most reported NR-based stretchable strain sensor. Meanwhile, the sensor also exhibits stable strain sensing behavior under different amplitude of human motions such as finger, wrist, elbow, and knee joint bending. Our work provides more opportunities for the design of effective elastomeric conductors in the application of wearable electronic devices.