Biological sensing with magnetic nanoparticles using Brownian relaxation (invited)

S. H. Chung, A. Hoffmann, K. Guslienko, S. D. Bader, C. Liu, B. Kay, L. Makowski, L. Chen

Research output: Contribution to journalArticlepeer-review


Magnetic nanoparticles coated with biochemical ligands are enabling many biological and medical applications. In particular biomagnetic sensors have potential advantages of simplicity and rapidity. We demonstrate a substrate-free biomagnetic sensing approach using the magnetic ac susceptibility of ferromagnetic particles suspended in a liquid. The magnetic relaxation of these particles is mainly due to Brownian rotational diffusion, which can be modified by binding the particles to the intended target. This scheme has several advantages: (i) it requires only one binding event; (ii) there is an inherent check of integrity; and (iii) the signal contains additional information about the target size.

Original languageEnglish (US)
Article number10R101
JournalJournal of Applied Physics
Issue number10
StatePublished - May 15 2005
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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