title: Continuous cytometric bead processing within a microfluidic device for bead based sensing platforms.
abstract: A microfluidic device for continuous biosensing based on analyte binding with cytometric beads is introduced. The operating principle of the continuous biosensing is based on a novel concept named the "particle cross over" mechanism in microfluidic channels. By carefully designing the microfluidic network the beads are able to "cross-over" from a carrier fluid stream into a recipient fluid stream without mixing of the two streams and analyte dilution. After crossing over into the recipient stream, bead processing such as analyte-bead binding may occur. The microfluidic device is composed of a bead solution inlet, an analyte solution inlet, two washing solution inlets, and a fluorescence detection window. To achieve continuous particle cross over in microfluidic channels, each microfluidic channel is precisely designed to allow the particle cross over to occur by conducting a series of studies including an analogous electrical circuit study to find optimal fluidic resistances, an analytical determination of device dimensions, and a numerical simulation to verify microflow structures within the microfluidic channels. The functionality of the device was experimentally demonstrated using a commercially available fluorescent biotinylated fluorescein isothiocyanate (FITC) dye and streptavidin coated 8 microm-diameter beads. After, demonstrating particle cross over and biotin-streptavidin binding, the fluorescence intensity of the 8 microm-diameter beads was measured at the detection window and linearly depends on the concentration of the analyte (biotinylated FITC) at the inlet. The detection limit of the device was a concentration of 50 ng ml(-1) of biotinylated FITC.
authors.affiliation: Department of Mechatronics, School of Information and Mechatronics, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea. syang@gist.ac.kr
authors.forename: Sung
authors.initials: S
authors.lastname: Yang
authors.forename: Akif
authors.initials: A
authors.lastname: Undar
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Zahn
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D001710:Biotin; D016650:Fluorescein-5-isothiocyanate / Q000032:analysis; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*; D008863:Microspheres
chemical_list: D001710:Biotin; D016650:Fluorescein-5-isothiocyanate