Magnetic biosensing

At Imego we use magnetic nanoparticles in biosensor applications to study how the Brownian relaxation (random particle rotation) time changes when biomolecules bind to the surface of particles. We use magnetic induction techniques to study the changes in Brownian relaxation. This requires that the orientation of the magnetic moment of the particle must change at the same rate as the rotation time of the particle itself. The orientation of the magnetic moments in the single domains must then be constant, meaning that the whole magnetic particle (that can contain several single-domains locked in a solid matrix) must contain thermally blocked single-domains.

There are other biosensor systems that are related to magnetic detection of magnetic particles. These biosensor systems use SQUIDs (Superconducting Quantum Interference Devices) or sensitive GMR (Giant Magnetic Resistance Sensors) to detect the presence of magnetic particles. The sizes of the single-domains are dependent on the technique used and it is possible to find both superparamagnetic as well as thermally blocked particles in these applications.