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The ability of the Lorentz force to link a mechanical displacement to anelectrical current presents a strong interest for medical acoustics, and threeapplications were studied in this thesis. In the first part of this work, ahydrophone was developed for mapping the particle velocity of an acousticfield. This hydrophone was constructed using a thin copper wire and an externalmagnetic field. A model was elaborated to determine the relationship betweenthe acoustic pressure and the measured electrical current, which is induced byLorentz force when the wire vibrates in the acoustic field of an ultrasoundtransducer. The built prototype was characterized and its spatial resolution,frequency response, sensitivity, robustness and directivity response wereinvestigated. An imaging method called Lorentz Force Electrical ImpedanceTomography was also studied. In this method, a biological tissue is vibrated byultrasound in a magnetic field, which induces an electrical current by Lorentzforce. The electrical impedance of the tissue can be deduced from themeasurement of the current. This technique was applied for imaging a gelatinphantom, a beef muscle sample, and a thermal lesion in a chicken breast sample.This showed the method may be useful for providing additional contrast toconventional ultrasound imaging. Finally, this thesis demonstrated that shearwaves can be generated in soft tissues using Lorentz force. This work wasperformed by applying an electrical current with two electrodes in a soft solidplaced in a magnetic field. Shear waves were observed in gelatin phantom andliver sample. The speed of the shear waves were used to compute elasticity andtheir source to map the electrical conductivity of the samples.

Applications of Lorentz force in medical acoustics: Lorentz force  hydrophone, Lorentz Force Electrical Impedance Tomography, Imaging of shear  waves induced by Lorentz force