Flexible LIG-Based Breathing Rate Sensor With Skin-Contact Recovery for Smart Masks Using Capacitive Readout

Wearable breath sensors are critical for real-time respiratory monitoring, particularly in smart mask applications. Here, we present a flexible laser-induced graphene (LIG)-based breath sensor with robust recoverability from skin contact, ensuring consistent performance in dynamic wearable environments. The sensor integrates closely spaced interdigitated electrodes with LIG and is evaluated using both resistive and capacitive readout to determine the optimal sensing mechanism. The capacitive readout approach demonstrates higher sensitivity and stability in detecting breath patterns while mitigating signal drift caused by direct skin contact. The LIG structure offers intrinsic flexibility, lightweight properties, and excellent electrical conductivity, making it well-suited for integration into smart masks. Experimental results show high stability, rapid response, and reliable recovery with sensor responses up to 92.5% for capacitive readout, validating the sensor's potential for continuous respiratory monitoring in healthcare, fitness tracking. This work advances the development of next-generation, non-invasive breath sensors for intelligent personal health monitoring.