Towards an electrowetting-based digital microfluidic platform for magnetic immunoassays.
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.
Schaller
Vincent
V
Department of Microtechnology and Nanoscience-MC2, Chalmers University of Technology, SE-412 96, Göteborg, Sweden. vincent.schaller@chalmers.se
Sanz-Velasco
Anke
A
Kalabukhov
Alexey
A
Schneiderman
Justin F
JF
Oisjöen
Fredrik
F
Jesorka
Aldo
A
Astalan
Andrea Prieto
AP
Krozer
Anatol
A
Rusu
Cristina
C
Enoksson
Peter
P
Winkler
Dag
D
D058874:Electrowetting / Q000295:instrumentation*; D004867:Equipment Design; D007118:Immunoassay / Q000639:trends*; D008280:Magnetics; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D053758:Nanoparticles / Q000737:chemistry