title: Towards an electrowetting-based digital microfluidic platform for magnetic immunoassays.
abstract: We demonstrate ElectroWetting-On-Dielectric (EWOD) transport and SQUID gradiometer detection of magnetic nanoparticles (MNPs) suspended in a 2 microl de-ionized water droplet. This proof-of-concept methodology constitutes the first development step towards a highly sensitive magnetic immunoassay platform with SQUID readout and droplet-based sample handling. Magnetic AC-susceptibility measurements were performed on MNPs with a hydrodynamic diameter of 100 nm using a high-Tc dc Superconducting Quantum Interference Device (SQUID) gradiometer as detector. We observed that the signal amplitude per unit volume is 2.5 times higher for a 2 microl sample droplet compared to a 30 microl sample volume.
authors.affiliation: Department of Microtechnology and Nanoscience-MC2, Chalmers University of Technology, SE-412 96, Göteborg, Sweden. vincent.schaller@chalmers.se
authors.forename: Vincent
authors.initials: V
authors.lastname: Schaller
authors.forename: Anke
authors.initials: A
authors.lastname: Sanz-Velasco
authors.forename: Alexey
authors.initials: A
authors.lastname: Kalabukhov
authors.forename: Justin F
authors.initials: JF
authors.lastname: Schneiderman
authors.forename: Fredrik
authors.initials: F
authors.lastname: Oisjöen
authors.forename: Aldo
authors.initials: A
authors.lastname: Jesorka
authors.forename: Andrea Prieto
authors.initials: AP
authors.lastname: Astalan
authors.forename: Anatol
authors.initials: A
authors.lastname: Krozer
authors.forename: Cristina
authors.initials: C
authors.lastname: Rusu
authors.forename: Peter
authors.initials: P
authors.lastname: Enoksson
authors.forename: Dag
authors.initials: D
authors.lastname: Winkler
mesh_terms: D058874:Electrowetting / Q000295:instrumentation*; D004867:Equipment Design; D007118:Immunoassay / Q000639:trends*; D008280:Magnetics; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D053758:Nanoparticles / Q000737:chemistry