Cavitation effects in ultrasound-enhanced soft tissue adhesion

Hydrogel-tissue adhesives have a number of applications including wound dressing and regenerative medicine. It has been recently shown that submitting a soft tissue covered with a viscous binding matrix to ultrasound treatment before patching it with hydrogel enhances the adhesion significantly. The exact mechanism responsible for this effect is unclear, but it is believed to be cavitation. The present study aims at confirming this hypothesis by numerically and experimentally exploring the influence of the various aspects of the ultrasound treatment: acoustic pressure field, cavitation inception on the surface, viscous absorption and shear-thinning behavior of the binding matrix. The pressure field around the ultrasonic horn is determined numerically for varying excitation amplitude and distance between the ultrasonic horn and the tissue. This allows for an approximation of the cavitation aggressiveness and of the surface area of the tissue affected, which can be compared with the experimentally observed spatial control of the adhesion.