A measurement system adapted to characterize at least one single magnetic object comprising: - a magnetic AMR/PHR sensor comprising: • an active surface on which at least one magnetic particle is deposited and including a magnetic probe with a closed loop shape, the magnetic probe being made in a structure chosen in the group consisting of a bi-layered structure including a ferromagnetic film and an anti-ferromagnetic film, a spin-valve structure including a ferromagnetic film, a metal, a ferromagnetic and an anti-ferromagnetic film, and a tri-layered structure including a ferromagnetic film, a metal and an anti-ferromagnetic film, • a first terminal , • a second terminal , both terminals facing each other and contacting with the magnetic probe , - a source adapted to inject an alternative current or voltage in the magnetic probe , the source being connected between the first and second terminals and the current or voltage vibrating at an exciting frequency, and - a voltage measurement device connected between the first and second terminals measuring the differential voltage between the pair of terminals , characterized in that it further comprises - a signal acquisition device adapted to extract the amplitude at twice the exciting frequency in the measured differential voltage and to deduce at least one physical quantity of the at least one magnetic particle based on the extracted amplitude. - a magnetic AMR/PHR sensor comprising: • an active surface on which at least one magnetic particle is deposited and including a magnetic probe with a closed loop shape, the magnetic probe being made in a structure chosen in the group consisting of a bi-layered structure including a ferromagnetic film and an anti-ferromagnetic film, a spin-valve structure including a ferromagnetic film, a metal, a ferromagnetic and an anti-ferromagnetic film, and a tri-layered structure including a ferromagnetic film, a metal and an anti-ferromagnetic film, • a first terminal , • a second terminal , both terminals facing each other and contacting with the magnetic probe , • an active surface on which at least one magnetic particle is deposited and including a magnetic probe with a closed loop shape, the magnetic probe being made in a structure chosen in the group consisting of a bi-layered structure including a ferromagnetic film and an anti-ferromagnetic film, a spin-valve structure including a ferromagnetic film, a metal, a ferromagnetic and an anti-ferromagnetic film, and a tri-layered structure including a ferromagnetic film, a metal and an anti-ferromagnetic film, • a first terminal , • a second terminal , both terminals facing each other and contacting with the magnetic probe , - a source adapted to inject an alternative current or voltage in the magnetic probe , the source being connected between the first and second terminals and the current or voltage vibrating at an exciting frequency, and - a voltage measurement device connected between the first and second terminals measuring the differential voltage between the pair of terminals , characterized in that it further comprises - a signal acquisition device adapted to extract the amplitude at twice the exciting frequency in the measured differential voltage and to deduce at least one physical quantity of the at least one magnetic particle based on the extracted amplitude. <EOS>