Ultrafast, Fabric‐Based Polyvinyl Alcohol‐Polyaniline Humidity Sensor for Wearable and Noninvasive Health Monitoring

The increasing demand for real‐time, contactless, and wearable sensing technologies has driven significant advances in humidity sensor design. Herein, a novel ultrafast, fabric‐based humidity sensor is presented, fabricated via a low‐cost dip‐coating method using a polyvinyl alcohol‐polyaniline composite on polypropylene fabric. The resulting device exhibits exceptional performance with a rapid response/recovery time of 4/6 ms, high linear sensitivity up to 99.9% over a wide relative humidity range (11%–95% RH), and long‐term stability with <2% deviation over 3 months. The sensor's selectivity to water vapor over various interfering gases underscores its robustness in mixed environments. Its ability to distinguish nasal and oral breathing patterns while capturing subtle physiological cues like moisture loss demonstrates strong potential for integration into next‐generation smart textiles and noninvasive health monitoring systems. This work uniquely demonstrates a low‐cost, fabric‐based humidity sensor with ultrafast response, high sensitivity, and long‐term stability, establishing a scalable pathway toward advanced wearable and contactless humidity sensing technologies.