Self-assembled magnetic bead chains for sensitivity enhancement of microfluidic electrochemical biosensor platforms

• Published in: Lab on a chip Vol. 15; no. 22; pp. 4314 - 4321
• Main Authors: Armbrecht, L, Dincer, C, Kling, A, Horak, J, Kieninger, J, Urban, G
• Format: Journal Article
• Language: English
• Published: England 01.01.2015
• Subjects: Beads; Biosensing Techniques - instrumentation; Biosensors; Channels; Chips; Electrochemical Techniques - instrumentation; Glucose Oxidase - analysis; Glucose Oxidase - metabolism; Hydrogen Peroxide - chemistry; Hydrogen Peroxide - metabolism; Magnetic Fields; Microfluidic Analytical Techniques - instrumentation; Microfluidics; Microspheres; Platforms; Self assembly; Streptavidin - chemistry
• ISSN: 1473-0197; 1473-0189; 1473-0189
• DOI: 10.1039/c5lc00796h

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.