Hierarchically engineered CNF-DE/GO composite films for high-performance piezoelectric–piezoresistive pressure sensing in wearable applications

The integration of piezoresistive and piezoelectric effects within a single matrix significantly enhances the multifunctionality of pressure sensors, enabling both precise pressure sensing and simultaneous energy harvesting. However, due to intrinsic material limitations, achieving dual-mode functionality in a single matrix has been considered highly challenging. In this study, we report a dual-mode pressure sensor based on a two-component single-matrix system, capable of exhibiting both piezoelectric and piezoresistive responses. The sensor is engineered by layer-by-layer self-assembly using cellulose nanofibers (CNFs) modified with dandelion extract (DE) and monolayer graphene oxide (GO). The resulting film exhibits excellent mechanical performance under aqueous conditions, with a tensile strength of 35.28 MPa and a fracture elongation of 10.25 %, attributed to the formation of a robust hydrogen-bonding network. For piezoelectric sensing, the sensor achieves a high d₃₃ values of 52.3 pC/N, a fast response time of 62 ms, and a peak induced voltage of 136 mV. Simultaneously, it demonstrates outstanding piezoresistive performance, including a high relative resistance change rate (ΔR/R₀ = 301), fast response/recovery times (20/20 ms), excellent cycling stability (over 1000 cycles), and a broad pressure detection range (6–620 kPa). This study presents a novel approach to CNF surface engineering and provides a scalable route to fabricate advanced dual-functional film sensors for next-generation wearable electronics and intelligent pressure monitoring systems.