A Flexible, Highly Sensitive Dual-Mode Temperature–Pressure Sensor with Waterproof Micropillar Structures for Wearable Physiological Sensing

Abstract Flexible electronic devices show great promise in health monitoring due to their wearability and skin compatibility. Comprehensive health assessment relies on multidimensional physiological information, which is difficult to achieve using single-modal sensing. Therefore, developing multimodal high-performance sensors is of great significance. This study proposes a flexible sensor for simultaneous temperature and pressure detection. The temperature-sensitive layer is fabricated by repeatedly dipping a textile fiber substrate into a uniform composite of polyaniline (PANI), reduced graphene oxide (rGO), and silicone rubber (SR), forming a stable three-dimensional conductive network that responds to temperature through its intrinsic thermosensitivity. Microstructural characterization and sensing mechanism analysis reveal the binding state between the conductive materials and the fiber substrate, clarifying the conductive network formation mechanism. This layer exhibits stable sensing performance from 25 to 60 °C, with a temperature coefficient of resistance of −1.14%/°C. The pressure-sensitive layer operates on a capacitive mechanism using a microstructure made of AB adhesive with a 3D-printed template. This design achieves a wide detection range of 0–137.1 kPa and a sensitivity of 1.11 kPa–1 in the 0–0.9 kPa range. To reduce signal coupling, a microstructure encapsulation strategy physically separates the two sensing pathways, reducing cross-sensitivity and enabling reliable multimodal monitoring in complex environments. Finally, the sensor is validated in applications including human joint motion monitoring, interactive security input, and intelligent water usage analysis, demonstrating its potential in wearable electronics and smart home systems.