Ultrasonic vibrational potentials in gels and preparations of biological tissue.

Measurements of the ultrasonic vibrational potentials (UVP) were performed at 815 kHz in agar and agarose gels as well as in several biological tissues from frog, rat and pig. The results for gels show that the magnitude of the UVP depends on the charge of the solid components of the gel, its mechanical strength and particularly on the concentration of free electrolytes present in the gel. The UVP decreases to less than 10 microV for a velocity amplitude of 1 cm/s if the salt concentrations exceed 10(-2) mol/L. The measurements in biological tissue in vitro demonstrate that the UVP are of the order of magnitude of a microV s cm-1 which is also explained by the presence of electrolytes of high concentrations in tissues. The measurements in biological tissue in vitro demonstrate that the UVP are of the order of magnitude of microV s cm-1 which is also explained by the presence of electrolytes of high concentrations in tissues. Based on these experiments, it can be concluded that the potential for harm to humans due to electrical effects of ultrasound as used in medical diagnostics is very low.