Magnetic force induced vibration on a ferromagnetic sphere for viscoelastic media characterization

Abstract

[EN] A new method that combines transient magnetic forces with ultrasonic imaging and allows the local experimental characterization of the complex shear modulus of a viscoelastic medium is presented. By measuring the dynamics of a ferromagnetic inclusion under the application of a magnetic force, the viscoelastic properties of the medium are extracted. The system is composed of a coil, which creates a magnetic field that induces displacement on a ferromagnetic particle located inside a test phantom, and an ultrasound transducer operating in pulsed-echo mode, utilized to track the displacement of the particle with spatial resolution of several um. Experiments were conducted embedding a ferromagnetic sphere on test phantoms with different compositions and at different temperatures. The obtained results are in good agreement with the theoretical estimation of the dynamical response of a sphere and show robustness on the estimation of the viscoelastic parameters. Moreover, temperature dependent results show asymptotic elasticity values which are physically consistent for soft-solid media.