Discussion

Starting with a proof of principle experiment, it is shown that the on-chip manipulation and transportation of magnetic particles works as well as the positioning of the particles in specific predefined places. Despite a few problems during the experiments and the preparation, all kinds of manipulations can be achieved with conducting lines on a chip. For nearly all transportation and positioning tasks, a specially designed structure can easily be prepared. It is shown that a small current ($\approx$5mA) is enough to manipulate the magnetic particles, and that the manipulation of a single particle is possible. The accuracy of positioning magnetic beads only depends on the accuracy of the lithography method.

The behaviour of a single particle in a hydrodynamic system was simulated by JAN STALLKAMP in 2003 [118]. The recent method of LATTICE-BOLTZMANN-simulations enables deeper insight into the behaviour of colloidal systems, and is especially interesting for particles with attached biomolecules.

After this general approach to the on-chip manipulation and positioning, two special applications will be presented. In chapter 4, a manipulation method will be used to measure the bond-forces between two biomolecules. And finally, a single bead will be exactly positioned on top of a TMR-Sensor in chapter 6.