Phase-Programmed Ionogels Enabling Decoupled Strain-Temperature Sensing with Negligible Hysteresis and High Resolution for Intelligent Fitness Monitoring.

Yang, Kunkun; Wu, Zixuan; Xu, Yankang; Chen, Xianjie; Liu, Yuxing; Huang, Jiaming; Zhu, Jiahao; Hu, Kaijie et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

Simultaneous sensing of mechanical and thermal stimuli in soft ionotronics remains a challenge because ionic conductors couple thermal activation and mechanical deformation through shared transport pathways. Here, we report an ionogel platform achieving signal decoupling through a materials-to-architecture modulus programming. Polymerizing poly(acrylic acid) (PAA) inside hydrophilic-hydrophobic binary ionic liquids triggers solubility-driven phase separation, modulating the modulus from ∼10 kPa to ∼10 MPa. Architecturally, we engineered an alternating Hard-Soft-Hard ionogel array where interpenetrating PAA networks polymerize across the units to form chemically bonded interfaces without secondary bonding. The PAA-rich hard domains act as strain-invariant thermistors (local strain <0.04%), delivering 0.01 °C temperature resolution and negligible hysteresis (1.64%). Simultaneously, the soft domains function as linear strain and directional sensors. Integrating this platform with AI algorithms enables smart monitoring during fitness routines. Leveraging phase separation for functional partitioning offers a novel perspective on simplifying multimodal sensor design.