Janus Wettable Mask with Integrated Ratiometric Fluorescent Probe for Comfortable Exhaled HS Gas Sensing.

The exhaled HS gas is considered a promising noninvasive, rapid biomarker for diagnosing oral health and respiratory diseases. However, there is an urgent need in the healthcare industry for a sensitive, accurate, low-cost, and comfortable wearable breath sensor for HS detection. Herein, a Janus wettable mask was developed by integrating the ratiometric fluorescent probes and asymmetric wettable fabric into the interior of the mask, for the comfortable and visual detection of HS. The Janus wettable mask with unidirectional biofluid transport capabilities can quickly transfer liquids from the hydrophobic side to the hydrophilic side, ensuring the dryness of the face during prolonged mask wear. The fluorescent color change from red to blue on the mask sensor can be observed by the naked eye under ultraviolet light, which enables evaluation of the HS gas concentration within a linear range of 1-100 ppb, and a low detection limit of 0.8 ppb. On-body experiments confirmed that the mask accurately detects exhaled HS gas and effectively captures the dynamic variations in HS gas levels at different times of the day. This study provides new insights into developing user-friendly wearable sensors and offers innovative solutions for reducing the burden on healthcare systems.