Ultralow-threshold airflow sensor for noninvasive obstructive sleep apnea monitoring and intervention system

Obstructive sleep apnea (OSA) is a prevalent sleep disorder worldwide, with nasal and oral airflow serving as the most direct indicators of OSA-related respiratory events. Existing respiratory monitoring sensors require philtrum attachment or nasal insertion to capture clear signals, causing discomfort and reducing sleep quality. Capturing breathing airflow in a more comfortable, noninvasive manner remains a challenge, primarily due to the limited detection threshold and slow response of current airflow sensors. Inspired by mammalian vascular networks, we propose a pneumatically sprayed, multi-level, lightweight network (PSN) as the substrate for high performance hot-film sensors for the first time. The breathable PSN facilitates efficient heat exchange and minimizes thermal inertia, resulting in an ultralow detection threshold of 0.0015 m⸱s −1 (1.5 mm⸱s −1 ) and a rapid response time of 86 ± 8.9 ms, thereby placing it among the best-performing airflow sensors reported to date. Comparative studies with the gold-standard polysomnography demonstrate the PSN sensor's high accuracy in noninvasive breath-to-breath interval measurement. Furthermore, we developed a real-time OSA intervention system. The system detected prolonged breath-to-breath intervals in real time and triggered pillow actuation, demonstrating the feasibility of closed-loop positional intervention for apnea-related respiratory events. This work provides a cost-effective strategy for high-performance airflow sensors, and offers a comfortable, efficient home-based OSA management solution.