Acoustic Impedance Difference (Microbubble Resonance)

This target is not a molecule or receptor in the traditional biochemical sense, but rather a physical phenomenon and engineered agent used to enhance ultrasound imaging. The enhancement relies on the introduction of microbubbles into the bloodstream, which exploit differences in acoustic impedance between their gas core and surrounding tissues or fluids. When exposed to ultrasound waves, these microbubbles resonate—expanding and contracting rapidly—which dramatically increases their reflectivity compared to normal body tissues. This resonance can also be harnessed for targeted drug/gene delivery when combined with focused ultrasound energy.

Other names

Microbubble Contrast EnhancementUltrasound Contrast AgentsMicrobubble Imaging

Microbubbles resonate in response to ultrasound waves due to the large difference in acoustic impedance between the gas core and surrounding tissue, resulting in enhanced echo signals. This resonance can also be used for targeted drug delivery by increasing local membrane permeability or fragmenting bubbles for payload release.