title: Microbubble moving in blood flow in microchannels: effect on the cell-free layer and cell local concentration.
abstract: Gas embolisms can hinder blood flow and lead to occlusion of the vessels and ischemia. Bubbles in microvessels circulate as tubular bubbles (Taylor bubbles) and can be trapped, blocking the normal flow of blood. To understand how Taylor bubbles flow in microcirculation, in particular, how bubbles disturb the blood flow at the scale of blood cells, experiments were performed in microchannels at a low Capillary number. Bubbles moving with a stream of in vitro blood were filmed with the help of a high-speed camera. Cell-free layers (CFLs) were observed downstream of the bubble, near the microchannel walls and along the centerline, and their thicknesses were quantified. Upstream to the bubble, the cell concentration is higher and CFLs are less clear. While just upstream of the bubble the maximum RBC concentration happens at positions closest to the wall, downstream the maximum is in an intermediate region between the centerline and the wall. Bubbles within microchannels promote complex spatio-temporal variations of the CFL thickness along the microchannel with significant relevance for local rheology and transport processes. The phenomenon is explained by the flow pattern characteristic of low Capillary number flows. Spatio-temporal variations of blood rheology may have an important role in bubble trapping and dislodging.
authors.affiliation: School of Technology and Management (ESTiG), Polytechnic Institute of Bragança (IPB), Campus de Santa Apolónia, 5300-253, Bragança, Portugal.|Transport Phenomena Research Center (CEFT), Department of Chemical Engineering, Engineering Faculty, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.
authors.forename: David
authors.initials: D
authors.lastname: Bento
authors.affiliation: School of Technology and Management (ESTiG), Polytechnic Institute of Bragança (IPB), Campus de Santa Apolónia, 5300-253, Bragança, Portugal.
authors.forename: Lúcia
authors.initials: L
authors.lastname: Sousa
authors.affiliation: School of Technology and Management (ESTiG), Polytechnic Institute of Bragança (IPB), Campus de Santa Apolónia, 5300-253, Bragança, Portugal.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Yaginuma
authors.affiliation: School of Technology and Management (ESTiG), Polytechnic Institute of Bragança (IPB), Campus de Santa Apolónia, 5300-253, Bragança, Portugal.
authors.forename: Valdemar
authors.initials: V
authors.lastname: Garcia
authors.affiliation: MEtRiS, Department of Mechanical Engineering, Minho University, Campus de Azurém, 4800-058, Guimarães, Portugal.|Transport Phenomena Research Center (CEFT), Department of Chemical Engineering, Engineering Faculty, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.
authors.forename: Rui
authors.initials: R
authors.lastname: Lima
authors.affiliation: Transport Phenomena Research Center (CEFT), Department of Chemical Engineering, Engineering Faculty, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal. jmiranda@fe.up.pt.
authors.forename: João M
authors.initials: JM
authors.lastname: Miranda
mesh_terms: D056656:Lab-On-A-Chip Devices; D045423:Microbubbles; D012212:Rheology
keywords: Cell-free layer; Gas embolism; In vitro blood; Micro bubble; Microfluidics; Red blood cells