Particles can show a wide range of movement patterns according to the characteristic of the AC electric field applied: because of their induced dipole they can shift to high (or low) field regions, rotate or align to the field. Particle behaviour has a strong dependence on how freely ions can move along the surface. Functionalising the surface of the particle with biological molecules changes the current flow around the particle, modifying the direction and the speed of its motion. Using 4 electrodes, it is possible to induce a controlled movement of the particles, in our case we are working with orientation and rotation. The motion of the particle at different frequencies can be recorded with a computer and then analyzed to estimate surface electrical properties. Different chemical reactions on the surface will lead to different properties. The aim of the project is to detect binding events of antibodies and DNA to the particles, once they have been functionalised with the appropriate probe biomolecules.