Monitoring electric field induced changes in biological tissue by using ultrasound

A new effect resulting from the application of an electric field to biomaterials was discovered by analyzing ultrasound echo signals. The new effect was observed in ex-vivo biological tissues such as porcine heart, muscle, fat, and liver and tissue mimicking phantoms for an electric field were on the order of a few Volt/cm. Changes in the arrival time of ultrasound echoes were processed using cross-correlation based algorithms. The gradient of shifting along the ultrasound axis showed a strain in the direction perpendicular to the applied electric field. The electric field also lead to changes in the ultrasound echo amplitude. The amount of the strain and the echo amplitude change depended on the history of the applied electric field. The new effect cannot be explained by resistive heating, piezoelectric effect, or electrostriction. It might be related to the electrokinetic effects.