MHz range frequency based sensor for Magnetic Particle Detection

Design of rapid technique for magnetic particles detection based on inductive sensing is described in this paper. A fabricated 3D coil, oscillating at few MHz range frequencies, is used as a sensing element with its associated electronics for inductance measurements. Phase locked loop is used for sensor stability and accuracy in the detection system. The induced magnetic field, due to the presence of magnetic particles on the coil, alter the coil inductance and accordingly the output frequency signal. Different concentration and number of magnetic beads (µm to nm sizes) were tested with the sensor while oscillating at two different resonance frequencies and the results were compared together.