Biomimetic, mechanically strong silk fibroin/aramid nanofiber composite as piezoresistive sensor with excellent sensitivity and anti-liquid-interfering properties

Wearable sensor devices with sustainability, comfortability, advancement and versatility are increasingly in demand. Silk fibroin (SF)-based sensor devices are promising candidates due to their biocompatibility, biodegradability and low manufacturing cost. However, the existing SF-based sensor devices are difficult to achieve the excellent mechanical properties, high conductivity and anti-liquid-interfering properties. Aramid nanofibers (ANFs) with a high aspect ratio and excellent mechanical properties are usually served as the stiff segments to fabricate high-performance composites. Nevertheless, ANFs dispersion prepared via deprotonation exhibit high sensitivity to water, along with long preparation time (one week), limiting its practical applicability. Herein, inspired by the extraordinary mechanical properties of natural soft tissues, the silk fibroin/aramid nanofibers (SF/ANFs) composites were fabricated by the biomimetic hybridization between the SF and water-dispersible ANFs. The SF/ANFs composites showed higher mechanical properties than that of other previously reported SF-based composites, which were further modified with gold nanoparticles (Au NPs) and fluorocarbon (FC) resin to facilitate the integration of conductivity and hydrophobicity. As a result, the flexible and conductive SF/ANFs/Au@FC composite as piezoresistive sensor exhibited excellent sensitivity, broad pressure detection interval and anti-liquid interfering properties. This work presented a simple and time-saving procedure to prepare the water-dispersible ANFs, opening up new possibilities for hybridization with water-soluble materials. The mechanistic insights and manufacturability provided by the composite and sensor might present further opportunities for materials design and technological innovation.