Waterproof, Moisture‐Resistant, and Breathable Full‐Textile Iontronic Capacitive Pressure Sensor for Wearable Physiological Monitoring

Flexible iontronic capacitive pressure sensors enable precise and continuous monitoring of weak physiological signals owing to their high sensing capability, making them promising candidates for wearable health monitoring systems. However, such wearable iontronic pressure sensors, which retain a porous structure to ensure high breathability, inevitably experience significant signal drift and compromised operational stability caused by water or moisture penetration in practical applications. Herein, a fully textile‐based iontronic capacitive pressure sensor with a hydrophobic‐hydrophilic‐hydrophobic structure is proposed to address this challenge. In this design, the outer hydrophobic layer prevents external water penetration, and the middle hydrophilic layer absorbs moisture, while the inner hydrophobic layer blocks the absorbed moisture from reaching the sensing layer. This structure endows our pressure sensor with waterproofness, moisture resistance, and breathability, while the integration of a cotton fabric/poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP)/ionic liquid (IL) sensing layer significantly enhances its sensing performance. It exhibits a sensitivity of 11.61 kPa −1 and a fast response of 30 ms, while maintaining low signal drift in water and high‐moisture environments. Furthermore, the textile‐based structure allows the sensor to be breathable, improving wearable applicability. Such an iontronic pressure sensor exhibits great potential in pulse signal monitoring, serving as a feasible platform for wearable health monitoring systems.