title: Microflow cytometers with integrated hydrodynamic focusing.
abstract: This study demonstrates the suitability of microfluidic structures for high throughput blood cell analysis. The microfluidic chips exploit fully integrated hydrodynamic focusing based on two different concepts: Two-stage cascade focusing and spin focusing (vortex) principle. The sample--A suspension of micro particles or blood cells--is injected into a sheath fluid streaming at a substantially higher flow rate, which assures positioning of the particles in the center of the flow channel. Particle velocities of a few m/s are achieved as required for high throughput blood cell analysis. The stability of hydrodynamic particle positioning was evaluated by measuring the pulse heights distributions of fluorescence signals from calibration beads. Quantitative assessment based on coefficient of variation for the fluorescence intensity distributions resulted in a value of about 3% determined for the micro-device exploiting cascade hydrodynamic focusing. For the spin focusing approach similar values were achieved for sample flow rates being 1.5 times lower. Our results indicate that the performances of both variants of hydrodynamic focusing suit for blood cell differentiation and counting. The potential of the micro flow cytometer is demonstrated by detecting immunologically labeled CD3 positive and CD4 positive T-lymphocytes in blood.
authors.affiliation: Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin, Germany. marcin.frankowski@ptb.de
authors.forename: Marcin
authors.initials: M
authors.lastname: Frankowski
authors.forename: Janko
authors.initials: J
authors.lastname: Theisen
authors.forename: Andreas
authors.initials: A
authors.lastname: Kummrow
authors.forename: Peter
authors.initials: P
authors.lastname: Simon
authors.forename: Hülya
authors.initials: H
authors.lastname: Ragusch
authors.forename: Nicole
authors.initials: N
authors.lastname: Bock
authors.forename: Martin
authors.initials: M
authors.lastname: Schmidt
authors.forename: Jörg
authors.initials: J
authors.lastname: Neukammer
mesh_terms: D001773:Blood Cells / Q000166:cytology; D017252:CD3 Complex / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D002138:Calibration; D005434:Flow Cytometry / Q000295:instrumentation*; D016650:Fluorescein-5-isothiocyanate; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D057446:Hydrodynamics; D044085:Microfluidics / Q000295:instrumentation*; D055620:Optical Phenomena; D010799:Phycoerythrin / Q000378:metabolism; D012212:Rheology
chemical_list: D017252:CD3 Complex; D005456:Fluorescent Dyes; D010799:Phycoerythrin; D016650:Fluorescein-5-isothiocyanate