Biodegradable, robust, and conductive bacterial cellulose @PPy-P macrofibers as resistive strain sensors for smart textiles

Fiber-based resistive strain sensors have attracted significant interest in the development of smart wearable devices due to their portability, flexibility, and easy conformability. However, current fiber-based resistive strain sensors mainly composed of metals and nondegradable polymers are not environmentally friendly and have poor mechanical strength. In this work, we examined biodegradable, robust, and conductive macrofibers fabricated through the in situ polymerization of p-toluenesulfonic acid (P-TSA)-doped polypyrrole (PPy) in bacterial cellulose (BC) nanofibers using wet-stretching and wet-twisting methods. The BC/PPy-P macrofibers possessed excellent conductivity (~7.19 S/cm), with superior mechanical properties (~210 MPa tensile strength and 2 GPa Young's modulus). Importantly, the BC/PPy-P microfiber operating as a resistive strain sensor possessed fast response time (15 s) and long-term stability (up to 1000 cycles), which could be used to effectively detect human movements. Moreover, the matrix material BC of BC/PPy-P macrofibers could be completely degraded within 96 h in the cellulase solution, leaving only PPy-P particles that could be recycled for other use. Therefore, the prepared BC/PPy-P microfibers provided a promising strategy for developing green resistive strain sensing fibers, with great potential to design eco-friendly smart fabric for monitoring human movements.