title: Bubbles no more: in-plane trapping and removal of bubbles in microfluidic devices.
abstract: Gas bubbles present a frequent challenge to the on-chip investigation and culture of biological cells and small organs. The presence of a single bubble can adversely impair biological function and often viability as it increases the wall shear stress in a liquid-perfused microchannel by at least one order of magnitude. We present a microfluidic strategy for in-plane trapping and removal of gas bubbles with volumes of 0.1-500 nL. The presented bubble trap is compatible with single-layer soft lithography and requires a footprint of less than ten square millimetres. Nitrogen bubbles were consistently removed at a rate of 0.14 μL min(-1). Experiments were complemented with analytical and numerical models to comprehensively characterize bubble removal for liquids with different wetting behaviour. Consistent long-term operation of the bubble trap was demonstrated by removing approximately 4000 bubbles during one day. In a case study, we successfully applied the bubble trap to the on-chip investigation of intact small blood vessels. Scalability of the design was demonstrated by realizing eight parallel traps at a total removal rate of 0.9 μL min(-1) (measured for nitrogen).
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S3G9, Canada.
authors.forename: Conrad
authors.initials: C
authors.lastname: Lochovsky
authors.forename: Sanjesh
authors.initials: S
authors.lastname: Yasotharan
authors.forename: Axel
authors.initials: A
authors.lastname: Günther
mesh_terms: D000818:Animals; D001808:Blood Vessels; D004867:Equipment Design; D005740:Gases; D051379:Mice; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*; D044085:Microfluidics / Q000295:instrumentation*; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis
chemical_list: D005740:Gases; D009584:Nitrogen