Bidirectional Knitted Strain Sensor via AgNWs /MXene Hybridization for Broad-Range Multi-Stage Sensing

Abstract

We fabricated a bidirectional textile strain sensor via MXene/AgNWs functionalization of 2×2 double-knitted fabric, establishing a modulus-graded architecture (fabric > MXene > AgNWs) that enables concurrent 0-200% tensile and 0-20 kPa compressive sensing. Optimized at 4 mg/mL MXene, hydrogen bonding (-OH•••O-cellulose) enhances interfacial adhesion, yielding robust mechanics (3.19 MPa strength, 416% elongation). The structure leverages synergistic mechanisms: tensile strain triggers controlled AgNWs fracture cascades from MXene stress concentrators, achieving multi-stage sensitivity (GF = 10.15-101.80) with ultra-low detection limit (0.033% strain) and rapid response (288/384 ms). Compression induces topological loop compaction, delivering dual-regime linearity (6.53 kPa⁻¹ <3 kPa; 1.58 kPa⁻¹ >5 kPa), minimal hysteresis (<3%), and 500-cycle stability. Validated by physiological signal monitoring (pulse waveforms, joint kinematics) and extreme-strain durability (250% tension/42% compression), this platform bridges broad-range detection with high sensitivity for smart textiles and precision healthcare diagnostics.