SQUID-based bioassay with magnetic particles in flow

Abstract

We present preliminary results for a magnetic flow spectrometer for magnetic microparticle separation, and a magnetic flow cytometer for particle identification. The application of the instrument is to high-throughput bioassay. Here we report on the first application of our magnetic spectrometer to the sorting of ferromagnetic and superparamagnetic microspheres in flow. The system is based on a permanent magnet quadrupole and separates the polymer coated magnetic microspheres based on their magnetic moments. The cryogenic section of our magnetic flow cytometer, which involves SQUID-based detection of the sorted magnetic microspheres based on their magnetic moments, has been re-engineered to permit a smaller standoff between the SQUID array and the flowing magnetic particles. We present preliminary results with the new experimental setup, with an emphasis on both spatial and signal resolution. © 2006 IOP Publishing Ltd.