Effect of high intensity ultrasound on soft materials

High intensity ultrasound are known to exert steady forces on interfaces between medium with different acoustic impedance. This effect, the so called acoustic radiation pressure, has been widely studied in newtonian fluids and have found applications in some industrial and therapeutical processes. However, to our knowledge it has not been used in the context of soft materials. The aim of my thesis is to use this effect to act on the microstructure of several soft materials.
First, I will present rheological measurements performed on a carbopol microgel and an attempt to recover those results with an acoustic microrheology. Then I will show that it is possible to fluidize a granular packing with high intensity ultrasound and describe properties of the observed fluidization. Finally, I will show preliminary results on the effect of vibrations on the rheologoy of a carbon black colloidal gel.