The potential induced in anisotropic tissue by the ultrasonically-induced Lorentz force.
In the presence of a magnetic field, an ultrasonic wave propagating through tissue will induce Lorentz forces on the ions, resulting in an electrical current. If the electrical conductivity is anisotropic, this current is tilted toward the fiber direction, causing charge to accumulate between half-wavelengths: positive charge where the current vectors converge and negative where the current vectors diverge. This charge produces an electric field in the direction of propagation that is associated with an electrical potential, and this electric field causes an additional current that is also tilted by the anisotropy. The final result is the total current pointing perpendicular to the direction of propagation and a charging of the tissue every half wavelength. The potential has a greater magnitude than that obtained from colloidal suspensions or ionic solutions (ultrasonic vibration potentials) and may be used as the basis of a technique to image conductivity.
Tseng
Nancy
N
University of Michigan, Ann Arbor, MI 48109, USA.
Roth
Bradley J
BJ
D016880:Anisotropy; D004553:Electric Conductivity; D004594:Electrophysiology; D006801:Humans; D008280:Magnetics; D008954:Models, Biological; D014465:Ultrasonics