title: Maintaining monodispersity in a microbubble population formed by flow-focusing.
abstract: The dynamic processes impacting the size distributions of lipid-encapsulated microbubbles formed by flow-focusing were observed by video optical microscopy. Parameters studied included the filling gas, gas saturating the surrounding solution, and microbubble size (initial size 2-12 microm) to simulate typical laboratory conditions. Typically, dissolution or growth, followed by Ostwald ripening at a collection cover glass, were observed and quantified. However, in the case of small nitrogen-filled microbubbles surrounded by an air-saturated solution, Ostwald ripening was avoided for at least 9 h. These bubbles had a final size distribution of 1.5 +/- 0.1 microm. This work suggests that lipid-encapsulated microbubbles formed by flow-focusing should be given sufficient time to reach a terminal size before coming into contact with each other. These long-lived mondisperse microbubbles should be of interest in ultrasound contrast agents, microfabrication, food, and research applications.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, California 95616, USA.
authors.forename: Esra
authors.initials: E
authors.lastname: Talu
authors.forename: Kanaka
authors.initials: K
authors.lastname: Hettiarachchi
authors.forename: Robert L
authors.initials: RL
authors.lastname: Powell
authors.forename: Abraham P
authors.initials: AP
authors.lastname: Lee
authors.forename: Paul A
authors.initials: PA
authors.lastname: Dayton
authors.forename: Marjorie L
authors.initials: ML
authors.lastname: Longo
mesh_terms: D000388:Air; D045423:Microbubbles; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods; D009584:Nitrogen / Q000737:chemistry*; D010316:Particle Size; D014783:Viscosity
chemical_list: D009584:Nitrogen