Bioinspired 3D-Nanoprinted Optical Sensilla for Bidirectional Respiratory Monitoring.

Chronic respiratory diseases (CRDs) are the leading causes of death worldwide. Monitoring both inhalation and exhalation is crucial for lung function assessment and patient outcomes. However, current sensors lack sufficient stability and also lack the ability to differentiate between inhalation and exhalation, limiting clinical effectiveness. Inspired by bat-wing hair structures, we report an all-optical fiber sensilla for bidirectional airflow detection. Optical Merkel cells and microhairs are integrated at the fiber tip through femtosecond laser 3D nanoprinting. Bidirectional airflow interacts with the hair structures, inducing opposing nanoscale deformations of the Merkel cells, which causes spectral drift in different directions. The device enables bidirectional flow detection with sensitivities of 19.16 nm/(L/min) and -24.46 nm/(L/min), a record-high stability over 10,000 cycles. The ultracompact design allows seamless integration into trachea or masks. The device effectively identifies respiratory patterns, distress signals, and apnea signs, providing a noninvasive and precise tool for CRD management and emergency response.