title: Self-assembled magnetic bead chains for sensitivity enhancement of microfluidic electrochemical biosensor platforms.
abstract: In this paper, we present a novel approach to enhance the sensitivity of microfluidic biosensor platforms with self-assembled magnetic bead chains. An adjustable, more than 5-fold sensitivity enhancement is achieved by introducing a magnetic field gradient along a microfluidic channel by means of a soft-magnetic lattice with a 350 μm spacing. The alternating magnetic field induces the self-assembly of the magnetic beads in chains or clusters and thus improves the perfusion and active contact between the analyte and the beads. The soft-magnetic lattices can be applied independent of the channel geometry or chip material to any microfluidic biosensing platform. At the same time, the bead-based approach achieves chip reusability and shortened measurement times. The bead chain properties and the maximum flow velocity for bead retention were validated by optical microscopy in a glass capillary. The magnetic actuation system was successfully validated with a biotin-streptavidin model assay on a low-cost electrochemical microfluidic chip, fabricated by dry-film photoresist technology (DFR). Labelling with glucose oxidase (GOx) permits rapid electrochemical detection of enzymatically produced H2O2.
authors.affiliation: Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany. Can.Dincer@imtek.de.
authors.forename: L
authors.initials: L
authors.lastname: Armbrecht
authors.affiliation: Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany. Can.Dincer@imtek.de and Freiburg Materials Research Center - FMF, University of Freiburg, 79110 Freiburg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Dincer
authors.affiliation: Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany. Can.Dincer@imtek.de.
authors.forename: A
authors.initials: A
authors.lastname: Kling
authors.affiliation: Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany. Can.Dincer@imtek.de and Division of Chemical Protein Engineering, KTH Stockholm, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Horak
authors.affiliation: Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany. Can.Dincer@imtek.de.
authors.forename: J
authors.initials: J
authors.lastname: Kieninger
authors.affiliation: Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany. Can.Dincer@imtek.de and Freiburg Materials Research Center - FMF, University of Freiburg, 79110 Freiburg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Urban
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D055664:Electrochemical Techniques / Q000295:instrumentation*; D005949:Glucose Oxidase / Q000032:analysis / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000378:metabolism; D060526:Magnetic Fields; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D008863:Microspheres; D019809:Streptavidin / Q000737:chemistry
chemical_list: D019809:Streptavidin; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase