Colloid vibration current

Colloid vibration current is an electroacoustic phenomenon that arises when ultrasound propagates through a fluid that contains ions and either solid particles or emulsion droplets.

[1][2] The pressure gradient in an ultrasonic wave moves particles relative to the fluid.

The picture shows ions dragged towards the left hand pole.

As a result of this charge excess, particles gain a dipole moment.

[2] This phenomenon is widely used for measuring zeta potential in concentrated colloids.