Abstract
A micromagnetometry system for detecting the presence of very small quantities of magnetic particles comprises a first magnetic hybrid AMR/PHR multi-ring sensor (4) using a Wheastone bridge electrical configuration, a first current source (6), a first voltage measurement device (8), a set of at least one magnetic particles (12) deposited on the first magnetic sensor (4) and a processing unit (22) for detecting from a set of different measured differential voltages a magnetic flux shift representative of the presence of a least one deposited magnetic particle (12). The micromagnetometry system comprises means (20) for creating a magnetic excitation field HAC to make produce by each motionless magnetic particle (12) a stray magnetic field oscillating along the time at a constant frequency ranging from 10 Hz to 3 KHz.