A highly sensitive humidity sensor based on a PANI/MWCNTs needle-like three-dimensional nano-network structure

Abstract Multiwalled carbon nanotubes (MWCNTs) exhibit excellent electrical conductivity; however, their poor water absorption severely hinders their use in humidity-sensitive applications. To overcome this constraint and impart semiconducting properties with enhanced humidity sensitivity, we fabricated a polyaniline (PANI)/MWCNTs composite sensor by integrating conductive PANI onto MWCNTs via an in situ polymerization strategy. Systematic electrical characterization indicates that the sensor exhibits superior performance, characterized by excellent reproducibility, high linearity ( R 2 = 0.995), low hysteresis of 6.9% relative humidity (RH), and robust stability across a working temperature range of 30.8–56.7 °C. Morphological analysis confirms that the PANI coating self-assembles into a needle-like three-dimensional network on the MWCNTs surface, creating a hierarchical heterostructure. This architecture facilitates a synergistic dual-conduction mechanism that simultaneously promotes electron transport and enhances overall humidity-sensing capabilities. This work presents a promising strategy for optimizing conductive polymer-modified carbon materials for advanced humidity-sensing applications.