Rigid–flexible synergy in luffa-derived carbon aerogel: Ultra-low shrinkage, high elasticity, and cycle-stable wearable piezoresistive sensing

Transforming abundant agricultural waste into high-performance flexible electronic materials is a key challenge in achieving sustainable development goals, typically hindered by severe structural degradation and performance loss of biomass during pyrolysis. To overcome this problem, the current study proposes a “rigidity–flexibility coupled” structural anchoring strategy. Herein, the natural rigid microtubular skeleton of waste luffa vine fiber (LVF) is ingeniously integrated with the flexible molecular chains of sodium alginate (SA) and the nanosheets of graphene oxide (GO) at multiple scales. Through directional freezing to construct an ordered structure, it is found that the hydrogen bonds between LVF and SA drive the formation of a semi-interpenetrating polymer network. This along with the physical crosslinking effect of GO, effectively “locks” the fine structure precursor during the high-temperature carbonization, significantly suppressing the volume shrinkage by 64 %. The resulting carbon aerogel (CLVF-rGO-SA) exhibits a rare synergy of mechanical strength (8 kPa) and super-elasticity (height recovery rate >90 % after 500 cycles at 50 % strain). More importantly, its unique directional porous structure and graphene conductive network impart the material with exceptional piezoresistive sensing performance; i.e., high sensitivity of 1.37 kPa − ¹ , ultra-fast response of 58 ms, and extraordinary stability over 5000 cycles in the low-pressure range (0.1–10 kPa) relevant to human physiological signals. As a proof of concept, this sensor can accurately capture and distinguish complex human activities such as joint bending, swallowing, and pulse. This study not only presents a new paradigm for stabilizing the macroscopic structure of biomass at atomic and nanoscale but also opens up a sustainable avenue for converting agricultural waste into high-value flexible electronic devices. • “Rigidity–flexibility coupled” strategy upcycles luffa vine fiber into carbon aerogel. • The aerogel has a highly ordered, hierarchical porous structure for efficient stress conduction. • The sensor shows high sensitivity (1.37 kPa − ¹) and ultra-fast response (58 ms). • Sensor detects complex human signals like joint bending, swallowing, and pulse accurately.