A multifunctional wearable sensor based on Al₂O₃/liquid metal composite for simultaneous monitoring of pressure, proximity, and biaxial strain

Propose low-cost multimodal flexible mechanical sensor fabrication. • Build model for LM sensor resistance-strain prediction. • Simultaneously monitor proximity, pressure, biaxial strain signals. • Sensor realizes voice, cervical bending & head posture detection. Flexible wearable sensors hold considerable promise for health monitoring and human–machine interfaces; however, their widespread adoption remains hindered by intricate fabrication protocols, suboptimal interfacial adhesion, and electromechanical models lacking predictive accuracy. Herein, we report a facile, MEMS(Micro-Electro-Mechanical Systems)-free manufacturing strategy for a vertically stacked multifunctional sensor utilizing mechanochemically modified Al₂O₃/liquid metal (LM) composite. The semi-solid Al₂O₃/LM phase markedly enhances interfacial bonding with Ecoflex substrates, while template-guided blade coating enables micropatterning with 300 μm feature resolution. The integrated device combines dual-axial resistive strain sensing with capacitive pressure and proximity detection, facilitating simultaneous discrimination of orthogonal (x and y) strains, normal pressure (0.03–15 kPa), and object proximity. A refined numerical model is established to predict resistance evolution with high fidelity across 0–300% strain. The sensor demonstrates a strain detection range of 1%–400%, linear pressure sensitivity, and robust cycling stability over 10,000 stretch–release cycles. Its conformable integration onto human skin enables accurate monitoring of head movements and vocalization, underscoring substantial potential for wearable electronics and soft human–machine interfaces. Download: Download high-res image (246KB) Download: Download full-size image