Interfacial Molecular Ordering of PANI/MWCNT for Hazard and Vital Biophysical Signal Monitoring

ABSTRACT Next‐generation rescue technologies demand flexible, self‐powered sensors capable of simultaneously monitoring multiple hazards and vital signs in demanding field conditions. This study pioneers interfacial molecular ordering in polyaniline/multi‐walled carbon nanotube (PANI/MWCNT) composites via pulsed electrochemical polymerization, overcoming the limited interfacial control and random polymer dispersion of conventional PANI/CNT systems. By templating PANI growth on MWCNT bundles, we engineer a hierarchical “crystalline–quasi‐crystalline–amorphous” structure, where a ∼2 nm quasi‐crystalline PANI interlayer—stabilized by π–π stacking and van der Waals forces—enables directional carrier transport (carrier mobility increased by 133%, power factor sextupled). This atomic‐level ordering unlocks unprecedented multi‐mode sensing capabilities: (1) hazard monitoring with Nernstian pH response (59.35 mV pH ⁻¹ ) and ultrafast NH ₃ detection (0.81 s @ 5 ppm), based on reversible doping and depletion‐layer modulation; (2) biophysical tracking via Seebeck‐driven temperature/respiration sensing and pressure‐responsive joint/facial/vocal monitoring. Integrated into wearable firefighting gear, the composite simultaneously maps chemical threats, ambient temperature, and vital signs for triggering an alert. This interfacial engineering strategy redefines multifunctional sensing platforms for extreme‐environment rescue operations.