Adhesion of Microdroplets on Water-Repellent Surfaces toward the Prevention of Surface Fouling and Pathogen Spreading by Respiratory Droplets.

Biofouling caused by the adhesion of respiratory microdroplets generated in sneezing and coughing plays an important role in the spread of many infectious diseases. Although water-repellent surfaces are widely used for the long-term repellency of aqueous solutions, their repellency to pathogen-containing microdroplets is elusive. In this work, microdroplets from picoliter to nanoliter were successfully generated in a controlled manner to mimic the exhaled microdroplets in sneezing and coughing, which allowed us to evaluate the adhesion of microdroplets on both superhydrophobic and lubricant-infused "slippery" surfaces for the first time. The impact and retention of water microdroplets on the two water-repellent surfaces are compared and investigated. Microdroplet-mediated surface biofouling and pathogen transmission were also demonstrated. Our results suggested that the adhesion of microdroplets should be duly considered in the design and application of water-repellent surfaces on biofouling prevention.