Focused-ultrasound blood-brain-barrier opening

Transient, reversible, spatially-targeted opening of the blood-brain barrier by combining low-pressure focused ultrasound with intravenously-injected microbubbles: the bubbles oscillate (stable cavitation) within the focal vessels, mechanically loosening endothelial tight junctions so that drugs, antibodies, or gene-therapy vectors can cross into a chosen brain region for a few hours before the barrier reseals.

For neurotechnology this is a potential non-invasive delivery route for the very actuators that other frontier interfaces need — optogenetic, chemogenetic, or sonogenetic transgenes delivered to a focal, ultrasound-defined volume without surgery. It is in human trials for indications such as Alzheimer's disease, glioma, and ALS; the safety envelope depends on tight cavitation control, usually via real-time passive cavitation monitoring to keep bubbles oscillating stably rather than collapsing inertially.