Eco-friendly smart strain sensors: Influence of Cu-nanoparticles on electrical and piezo-resistive performance of sustainable sisal fiber-reinforced thermoplastic elastomers

The development of sustainable self-sensing composites remains limited by the lack of recyclable polymer matrices reinforced with natural fibers that can simultaneously deliver adequate mechanical performance and reliable electrical functionality. Currently, a significant understanding of the mechanical behavior of fiber-reinforced composite structures, but an important gap in knowledge remains in the way Cu nanoparticles influence the electromechanical performance of thermoplastic elastomer/sisal composites. Consequently, this work aims to bridge the gap in understanding the effect of Cu nanoparticles on the electrical conductivity and piezo-resistive behavior of these composite materials. Sandwich laminates were manufactured using thermoplastic elastomer as matrix and sisal fibers coated with copper nanoparticles whose molar concentrations ranged from 0.2 to 0.8 M. The test specimens were tested via FTIR, scanning electron microscopy, and electromechanical tensile tests to evaluate piezo-resistive behavior. The microscopic observations showed that the 0.8 M test sample had an even nanoparticle distribution as well as better interlocking. The Young’s modulus reached 0.59 GPa, while 9.64 MPa for tensile strength. Also, electrical conductivity increased proportionally with molarity reching its higher value at 0.8 M (5.30 × 10 ⁻¹ S.m ⁻¹ ). These findings demonstrate that combining Cu nanoparticle-functionalized sisal fibers with a recyclable thermoplastic elastomer matrix constitutes a promising strategy for developing eco-friendly multifunctional composites for smart sensing applications within a circular economy framework.