Optimizing Poly(vinyl alcohol) Organogel Sensor Performance at Ultralow Temperatures via Synergistic Modulation of Forces and Crystallization

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Achieving a delicate balance between mechanical performance and sensitivity is crucial for enhancing the responsiveness of hydrogel sensors to human body deformation signals, especially in ultralow-temperature sensing scenarios. This study introduces a solvent replacement method utilizing poly(vinyl alcohol) (PVA) in both dimethyl sulfoxide (DMSO) and a water-free mixed alcohol solution, combined with chemical cross-linking, to fabricate a resilient organogel. Substituting DMSO with a mixed alcohol solution reinforces interactions among PVA molecular chains, inducing crystallization and forming a uniform polymer network through cross-linking with dialdehyde alginic acid sodium salt. The introduction of Ca 2+ ions during solvent replacement significantly enhances organogel conductivity, elevating it from 1.28 to 20.16 mS/m. Optimization of cross-linking and crystallinity achieves excellent mechanical properties (σ = 10.2 MPa; ε = 8.47) and sensitivity (gauge factor of 2.486; response time = 170 ms) in the PVA organogel sensor. Employing a water-free mixed alcohol system ensures molecular chain mobility even at extreme temperatures, reducing the gel system’s freezing point and ensuring excellent sensing performance at −60 °C and lower. This innovative approach successfully overcomes the inherent trade-off between strength and sensitivity, addressing the challenge of performance failure under extremely low-temperature environments in hydrogel-based strain sensors, demonstrating significant potential for smart wearable applications.