title: Centrifugo-dynamic inward pumping of liquids on a centrifugal microfluidic platform.
abstract: We present a method to pump liquids in a centrifugal microfluidic spinning disk from a radial outward position to a radial inward position. Centrifugal forces are applied to compress air in a cavity, this way storing pneumatic energy. The cavity is connected to an outlet channel having a lower hydraulic resistance compared to the inlet channel. The stored pneumatic energy is quickly released by fast reduction of rotational frequency. This way liquid is transported mainly through the channel with lower resistance, directing the liquid radially inwards. Pump efficiencies of >75% per pump cycle have been demonstrated for water, ethanol, a highly viscous lysis buffer and whole blood. By employing three pump cycles, water has been pumped radially inwards with an efficiency of >90%. The inward pumping requires centrifugation only, which is intrinsically available on every centrifugal microfluidic platform.
authors.affiliation: HSG-IMIT - Institut für Mikro- und Informationstechnik, Georges-Koehler-Allee 103, 79110 Freiburg, Germany. steffen.zehnle@hsg-imit.de
authors.forename: Steffen
authors.initials: S
authors.lastname: Zehnle
authors.forename: Frank
authors.initials: F
authors.lastname: Schwemmer
authors.forename: Günter
authors.initials: G
authors.lastname: Roth
authors.forename: Felix
authors.initials: F
authors.lastname: von Stetten
authors.forename: Roland
authors.initials: R
authors.lastname: Zengerle
authors.forename: Nils
authors.initials: N
authors.lastname: Paust
mesh_terms: D002498:Centrifugation / Q000295:instrumentation*; D057446:Hydrodynamics; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D008962:Models, Theoretical