Atomization by Acoustic\nLevitation Facilitates Contactless\nMicrodroplet Reactions

Microdroplet chemistry is now well-known to be able to\nremarkably\naccelerate otherwise slow reactions and trigger otherwise impossible\nreactions. The uniqueness of the microdroplet is attributable to either\nthe air–water interface or solid–liquid interface, depending\non the medium that the microdroplet is in contact with. To date, the\nimportance of the solid–liquid interface might have been confirmed,\nbut the contribution from the air–water interface seems to\nbe elusive due to the lack of method for generating contactless microdroplets.\nIn this study, we used a droplet atomization method with acoustic\nlevitation. Upon manipulation of the acoustic field, the levitated\nparent droplet can be further atomized into progeny microdroplets.\nWith this method, only the air–water interface was present,\nand a large variety of reactions were successfully tested. We anticipate\nthat this study can be an advance toward the understanding of the\nair–water interfacial processes of microdroplet chemistry.