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MA: Fachverband Magnetismus

MA 39: Magnetic Particles

MA 39.12: Talk

Thursday, March 10, 2016, 12:30–12:45, H31

Positioning and Detection of Magnetic Nanoparticles for Lab-on-Chip systems — •Benjamin Riedmüller, Shalini Easwardas, Florian Ostermaier, and Ulrich Herr — Institute für Mikro- und Nanomaterialien, Universität Ulm, Ulm, Deutschland

Magnetic nanoparticles are interesting in combination with magneto-resistive sensors for Lab-on-Chip systems. In such applications, superparamagnetic particles are typically used, to which biological analytes can be specifically bound. By detecting the particles, the presence of the bio-species can be confirmed. For detection, the particles have to be positioned in the vicinity of the active sensor area. Here, a common principle for positioning of superparamagnetic particles is the application of magnetic field gradients by which a force on the particles is generated. In a previous work we derived a quantitative model for the force on a superparamagnetic particle by a combination of the field gradient produced by tapered conductor lines and a superimposed, homogeneous magnetic field. By this, the limitation by which particles can only be attracted towards the conductor is overcome. We demonstrated that this approach allows positioning a single superparamagnetic particle in two dimensions on length scales > 100 um with a precision of < 1 um. Based on this technique a particle lens consisting of a conductor ring can be constructed by which a single particle is first guided and then fixed at a pre-defined position with high accuracy. Our results further show that these manipulation concepts can be easily combined with common micro-structured magneto-resistive sensors which allow the real-time detection of the motion of the particle.