Impedance Modulation by Pulsed Ultrasound

    loading  Checking for direct PDF access through Ovid



The propagation of an acoustic wave in an electrolyte solution produces local and periodic conductivity changes. This acousto-electrical interaction is due to the variations of the parameters controlling ionic conductivity against pressure and temperature. The overall effect is about 10−7 % Pa−1 for solutions of physiological ions and is practically independent of the ionic species involved. The bulk compressibility of the medium is responsible for about 47% of the effect, the change in viscosity due to pressure changes is responsible for about 18%, and the changes of ionic mobility against temperature are responsible for about 35%. Detectable impedance changes were produced in the focal zone of a 500-kHz focused transducer using moderate intensity ultrasound (peak pressure < 1 MPa). This technique potentially enables the association of the spatial resolution of pulsed ultrasound and impedance measurement, although technical improvements and feasibility studies are still needed prior to practical applications.

Related Topics

    loading  Loading Related Articles