Ultra-Wide-Range Linear Capacitive Pressure Sensors Enabled by a Micro-Encapsulated Aqueous-Silicone Dielectric Layer

Flexible pressure sensors are crucial for wearable electronics but face challenges in balancing high sensitivity, wide linear range, and high pressure resolution, particularly for detecting small fluctuations under high pressure. Here, we propose an ultrawide-range linear capacitive pressure sensor featuring a microencapsulated aqueous-silicone composite dielectric layer. By tuning the aqueous-to-silicone ratio in a stable water-in-oil emulsion, we synergistically control the elastic modulus and dielectric constant of the dielectric layer, enhancing sensitivity, pressure resolution, and linear range without relying on complex microstructures or conductive fillers. The sensor exhibits excellent linearity (R2 = 0.997) over an ultrawide pressure range of 0-1200 kPa, with a sensitivity of 0.015 kPa-1. It detects pressures as low as 100 Pa, maintains a resolution of 0.11% at 900 kPa, and withstands over 7000 loading-unloading cycles with remarkable durability. Furthermore, the sensor allows reliable monitoring of various physiological signals, including finger bending, neck motion, and swallowing activity. When integrated into a smart insole system with machine-learning algorithms, the sensor array achieves accurate recognition of ten human motion states with an average accuracy of 98.8%. These findings pave the way for the sensor's practical applications in wearable electronics, intelligent motion monitoring, and human-machine interaction systems.