Wide-Linear Flexible Iontronic Pressure Sensor Enabled by Nanoparticle Interfacial Modulation and Synergistic Effect

Abstract

Flexible ionic capacitive pressure sensors have attracted considerable interest for applications in wearable electronics, soft robotics, and human-machine interfaces. However, achieving high sensitivity typically relies on microstructured geometries (micro-pyramids), which increase fabrication complexity and reduce mechanical robustness. Here, we report an alternative strategy based on an organic-inorganic hybrid ionic medium composed of ionic liquid, polyurethane and dispersed ZnO/SiO₂ particles, fabricated via a scalable solution process. The inorganic components introduce complementary functionalities: The nanoparticle surfaces serve as weakly bound ionic reservoirs, confining ions through weak interactions while enabling their rapid release under pressure via local energy landscape perturbations. Meanwhile, the organic-inorganic interfaces establish high speed ion pathways by structural disorder and polar surface. Under mechanical loading, these effects collectively enable pressure-triggered ionic state transitions and accelerated ion redistribution, leading to more effective electrical double layer (EDL) formation during working. As a result, the sensor achieves a high sensitivity of 4.7 kPa⁻¹ with excellent linearity (R² = 0.996) over a wide pressure range from 1 Pa to 300 kPa. Demonstrations in gentle airflow detection, pressure mapping, and human-robot interaction highlight its versatility. This work provides a materials-based route to regulate EDL dynamics, offering a robust and scalable sensitivity enhancement in iontronic sensor.