摘要
All-polymer PVDF/PVA sea-island hydrogels are engineered by LLPS and NIPS. • Uniform PVDF islands improve stress transfer and promote electroactive phase formation. • Electroactive PVDF phase exceeds 95% with an effective piezoelectric response of 40.9 ± 1.6 pC N −1 . • Stable electromechanical sensing is maintained over 1600 loading cycles. • LSTM-assisted sensors enable personalized recognition of exercise patterns. Flexible piezoelectric materials are promising for wearable electronics and biosensing applications, yet achieving high electromechanical sensitivity while maintaining mechanical softness remains challenging for hydrogel-based systems. Herein, we report an all-polymer piezoelectric hydrogel with a controlled sea-island structure, engineered via coupled liquid-liquid phase separation and non-solvent-induced phase separation. The resulting architecture consists of uniformly dispersed PVDF islands embedded in a continuous PVA matrix. PVDF islands provide electroactive crystalline domains and contribute to stress transfer within the hydrated network, while the sea–island architecture and interfacial interactions synergistically enhance the effective piezoelectric response ( d 33,eff = 40.9 ± 1.6 pC N −1 ). The hydrogel sensors exhibit stable and sensitive responses to subtle biomechanical signals, including finger, face, throat and pulse monitoring. For exercise-related limb movements, the sensor signals were analyzed using a Long Short-Term Memory (LSTM) neural network under subject-independent validation, demonstrating the feasibility of signal-based discrimination between standard and non-standard movements. This work establishes a microstructure-engineering strategy for improving the mechanical and piezoelectric performance of PVDF/PVA hydrogels, enabling their application in wearable motion monitoring. Download: Download high-res image (214KB) Download: Download full-size image
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