Which cavitation form is characterized by stable bubble oscillation without collapse?

• A. Stable cavitation
• B. Transient cavitation
• C. Inertial cavitation
• D. Normal cavitation

Answer: (A)

When ultrasound interacts with microbubbles, they can either stay intact while repeatedly expanding and contracting, or they can grow rapidly and collapse violently. The form that shows stable bubble oscillation without collapse is stable cavitation, also called noninertial cavitation. It occurs at lower acoustic pressures, so the bubble gently pulsates in step with the pressure cycles and does not break apart. This sustained oscillation creates microstreaming around the bubble, producing shear forces that can influence nearby cells or enhance mixing, with relatively milder bioeffects.

In contrast, transient or inertial cavitation involves rapid bubble growth followed by a violent collapse, generating shock waves and higher local temperatures—effects that are much more disruptive and can risk tissue injury. The option “normal cavitation” isn’t a standard category for describing these behaviors.