Eco-Friendly All-Paper-Based Piezoresistive Sensor Based on BSA/CB/Carboxyl-Functionalized MWCNT Nanocomposites for Wearable Information Interaction

In recent years, growing attention has been directed toward the green and sustainable development of flexible electronic devices. The paper-based electronics gain significant research interest due to their unique advantages, including cost-effectiveness, good biocompatibility, and well conformability. In this study, an all-paper-based piezoresistive sensor is proposed for a portable information interaction. Innovatively, the sensing layer based on cellulose paper and bovine serum albumin/carbon black/carboxyl multiwalled carbon nanotubes (BSA/CB/MWCNTs) nanocomposites are prepared by using the layer-by-layer (LBL) assembly technique and interfacial interactions. By adoption of the synergistic mechanism based on hydrogen bonding and electrostatic interactions, the adhesion of the conductive nanomaterials is effectively improved. Meanwhile, the addition of carbon nanofibers (CNF) enhances the dispersion of the binary hybrid conductive filler in deionized water. The electrode layer with the interdigital electrode pattern is constructed on rice paper by using the screen-printing technology. This integrated approach not only improves the electromechanical performance of the composite but also maintains environmental sustainability. Besides, the effects of the proportion of the conductive filler and the number of dip coating times on the conductive network are investigated. The optimized sensor exhibits remarkable performance: an exceptional sensitivity of 89.71%/kPa, a rapid response/recovery time of 25 ms, and a broad detection range of up to 200 kPa. This work develops an eco-friendly flexible sensing technology based entirely on natural materials, offering a wearable solution for information interaction systems. This sensor is expected to provide design strategies for the development of sustainable electronic components in the era of green technology.