Microbubble

rdf:langString Microbubble

rdf:langString Microbubbles (MBs) are bubbles smaller than one hundredth of a millimetre in diameter, but larger than one micrometre. They have widespread application in industry, life science, and medicine. The composition of the bubble shell and filling material determine important design features such as buoyancy, , thermal conductivity, and acoustic properties. They are used in medical diagnostics as a contrast agent for ultrasound imaging. The gas-filled microbubbles, typically air or perfluorocarbon, oscillate and vibrate when a sonic energy field is applied and may reflect ultrasound waves. This distinguishes the microbubbles from surrounding tissues. In practice, because gas bubbles in liquid lack stability and would therefore quickly dissolve, microbubbles must be encapsulated with a solid shell. The shell is made from either a lipid or a protein such as Optison microbubbles which consist of perfluoropropane gas encapsulated by a serum albumin shell. Materials having a hydrophilic outer layer to interact with the bloodstream and a hydrophobic inner layer to house the gas molecules are the most thermodynamically stable. Air, sulfur hexafluoride, and perfluorocarbon gases all can serve as the composition of the MB interior. For increased stability and persistence in the bloodstream, gases with high molecular weight as well as low solubility in the blood are attractive candidates for MB gas cores. Microbubbles may be used for drug delivery, biofilm removal, membrane cleaning /biofilm control and water/waste water treatment purposes. They are also produced by the movement of a ship’s hull through water, creating a bubble layer; this may interfere with the use of sonar because of the tendency of the layer to absorb or reflect sound waves.