An anonymous reader writes with news of research from MIT, where
engineers have found a better way to use ultrasound waves to
boost the permeability of skin for the delivery of drugs.
"Ultrasound — sound waves with frequencies greater than the
upper limit of human hearing — can increase skin permeability by
lightly wearing away the top layer of the skin, an effect that
is transient and pain-free. ... When ultrasound waves travel
through a fluid, they create tiny bubbles that move chaotically.
Once the bubbles reach a certain size, they become unstable and
implode. Surrounding fluid rushes into the empty space,
generating high-speed 'microjets' of fluid that create
microscopic abrasions on the skin. In this case, the fluid could
be water or a liquid containing the drug to be delivered. In
recent years, researchers working to enhance transdermal drug
delivery have focused on low-frequency ultrasound, because the
high-frequency waves don’t have enough energy to make the
bubbles pop. However, those systems usuall