title: Controlled Lateral Positioning of Microparticles Inside Droplets Using Acoustophoresis.
abstract: In this paper, we utilize bulk acoustic waves to control the position of microparticles inside droplets in two-phase microfluidic systems and demonstrate a method to enrich the microparticles. In droplet microfluidics, different unit operations are combined and integrated on-chip to miniaturize complex biochemical assays. We present a droplet unit operation capable of controlling the position of microparticles during a trident shaped droplet split. An acoustic standing wave field is generated in the microchannel, and the acoustic forces direct the encapsulated microparticles to the center of the droplets. The method is generic, requires no labeling of the microparticles, and is operated in a noncontact fashion. It was possible to achieve 2+-fold enrichment of polystyrene beads (5 μm in diameter) in the center daughter droplet with an average recovery of 89% of the beads. Red blood cells were also successfully manipulated inside droplets. These results show the possibility to use acoustophoresis in two-phase systems to enrich microparticles and open up the possibility for new droplet-based assays that are not performed today.
authors.affiliation: Dept. Biomedical Engineering, Lund University , Box 118, S-221 00, Lund, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Fornell
authors.affiliation: Dept. Biomedical Engineering, Lund University , Box 118, S-221 00, Lund, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Nilsson
authors.affiliation: Dept. Biomedical Engineering, Lund University , Box 118, S-221 00, Lund, Sweden.
authors.forename: Linus
authors.initials: L
authors.lastname: Jonsson
authors.affiliation: Div. of Proteomics and Nanobiotechnology, Science for Life Laboratory, KTH Royal Institute of Technology, Box 1031, S-171 21 Solna, Sweden.
authors.forename: Prem Kumar
authors.initials: PK
authors.lastname: Periyannan Rajeswari
authors.affiliation: Div. of Proteomics and Nanobiotechnology, Science for Life Laboratory, KTH Royal Institute of Technology, Box 1031, S-171 21 Solna, Sweden.
authors.forename: Haakan N
authors.initials: HN
authors.lastname: Joensson
authors.affiliation: Dept. Biomedical Engineering, Lund University , Box 118, S-221 00, Lund, Sweden.|Dept. Engineering Sciences, Science for Life Laboratory, Uppsala University , Box 534, S-751 21 Uppsala, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Tenje
mesh_terms: D055252:Cell-Derived Microparticles / Q000737:chemistry*; D004867:Equipment Design; D004912:Erythrocytes / Q000737:chemistry*; D006801:Humans; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry; D013016:Sound; D013499:Surface Properties
chemical_list: D011137:Polystyrenes