A microbubble is a very small gas bubble suspended in a liquid. At this scale, surface tension and interactions with the surrounding fluid can strongly influence how it behaves, so it may not act like a larger air pocket. Ultrasound can make microbubbles oscillate or move in controlled ways, depending on the conditions and application.
Microbubbles matter in engineering and science because their motion can be used to affect nearby materials or fluids. In fabrication research, ultrasound and microbubbles may be explored as tools for making tiny devices, although the specific mechanism and device application depend on the process. In cybersecurity, the term is not itself a cyber threat; understanding it helps accurately describe systems that may rely on physical processes, which can be relevant when assessing their reliability, safety, or control.