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- Öisjöen, Fredrik, 1982, et al.
(författare)
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High-Tc SQUID gradiometer system for immunoassays
- 2008
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Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 21:3, s. Art. Nr. 034004-
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Tidskriftsartikel (refereegranskat)abstract
- A high-Tc dc SQUID (superconducting quantum interference device) gradiometer was developed for magnetic immunoassays where magnetic nanoparticles are used as markers todetect biological reactions. The gradiometer was fabricated on a 5 × 10 mm2 SrTiO3 bicrystal substrate and has a gradiometer resolution of 2.1 pT cm−1 Hz−1/2. A magnetic signal was detected from a sample of 1 μl of Fe3O4 nanoparticles in a 40 mg ml−1 solution kept in amicrocavity fabricated on Si wafers with Si3N4 membranes using MEMS (micro-electro-mechanical-systems) technology. It was found that volumes as small as 0.3 nl in principle would be detectable with our present device. This corresponds to a total number of particles of 2.2 × 107. The estimated average dipole moment per particle is 4.8 × 10−22 Am2.We are aiming at reading out immunoassays by detecting the Brownian relaxation of magnetic nanoparticles, and we also intend to integrate MEMS technology into our system.
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