Janus Photothermal Comfortable Face Mask for Environmental Pollutant Monitoring.

Recent respiratory outbreaks have accelerated the innovation of face masks from simple protective supplies to functional and integrated wearable sensors that providing valuable insights into personal health management and real-time environmental monitoring. Herein, we integrate a Janus photothermal comfortable face mask as a wearable sensor for environmental pollutant monitoring. A hydrophobic-hydrophilic micropatterned Janus polylactic acid (PLA) membrane realizes unidirectional transport of exhaled breath condensate from the inner hydrophobic layer to the outer hydrophilic micropatterns. The exhalation and photothermal materials synergistically promote the continuous evaporation of moisture in the micropatterns to ensure a comfortable relative humidity of about 30% of the face mask. Benefiting from the enrichment of targets on the face mask by continuous breathing, we successfully achieved the sensitive and selective detection of environmental pollutants, including hydrogen sulfide and formaldehyde, in the hydrophilic micropatterns. Such a photothermal sensory face mask, with its advantages of being comfortable, wearable, and noninvasive, has wide application prospects in personal health management and real-time environmental monitoring.