Towards an electrowetting-based digital microfluidic platform for magnetic immunoassays.

Schaller, Vincent; Sanz-Velasco, Anke; Kalabukhov, Alexey; Schneiderman, Justin F; Oisjöen, Fredrik; Jesorka, Aldo; Astalan, Andrea Prieto; Krozer, Anatol et al. · Lab Chip · 2009

basic_science · Level V

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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.

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