Ultrasound waves could make skin more permeable to drugs

The technique, which uses two ultrasound beams of different frequencies, could aid the development of needle-free vaccinations and drug-delivery systems, the researchers claim.

In a paper in the Journal of Controlled Release, MIT chemical engineers Prof Daniel Blankschtein and Prof Robert Langer and colleagues describe how two ultrasound beams, one of low frequency and the other of high frequency, effectively ‘wear away’ the top layer of the skin they are applied to, allowing drugs to make their way through the skin and into the bloodstream. The skin damage is temporary, they claim, and doesn’t cause any pain.

The technique works because of the behaviour of bubbles, according to the team. It involves pushing ultrasound energy into a layer of liquid on the skin. The sound waves generate bubbles in the liquid, which grow until they become unstable, then implode. This sends liquid rushing into the space left by the bubble, which generates a high-speed liquid microjet with enough energy to scratch the surface of the skin.