Untitled

Abstract

Microbubbles are bubbles smaller than one millimeter in diameter, but larger than one micrometer. Microbubbles designate air or gas filled microspheres suspended in a liquid carrier phase which generally results from the introduction of air or gas. The liquid phase contains surfactants to control the surface properties as well as stability of the bubble. Microbubbles have an average size less than that of RBC's i.e., they are capable of penetrating even into the smallest blood capillaries & releasing drugs or genes, incorporated on their surface, under the action of ultrasound. Microbubbles in general have a wide variety of applications. However in the biomedical field these are primarily used as diagnostic agents in combination with ultrasound for molecular imaging of various organs and even tumours. These are also proposed for drug and gene delivery to targeted regions in combination with various ligands. Most of the physicians today prefer imaging with ultrasound in combination with microbubbles compared to other diagnostic techniques for low cost and rapidity. They are used in medical diagnostics as a contrast agent for ultrasound imaging. The gas-filled, e.g., air or perfluorocarbon, microbubbles oscillate and vibrate when a sonic energy field is applied and may reflect ultrasound waves. This distinguishes the microbubbles from surrounding tissues. The unique ability of microbubbles to respond to ultrasound makes them useful agents for contrast ultrasound imaging, molecular imaging, and targeted drug and gene delivery. 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. Microbubbles may also be used for drug delivery and water/waste water treatment purposes. INTRODUCTION: Microbubbles are also small spherical bubbles comprising of gas, they remain distinct from each other or separate from each other i.e. do not agglomerate, also they have their size range in micrometers usually 1-100 µm. There has been a lot of research on micro bubbles in recent years. Micro bubbles are miniature gas bubbles of less than 50 microns diameter in water. The micro bubbles, which mostly contain oxygen or air, can remain suspended in the water for an extended period. Gradually, the gas within the micro bubbles dissolves into the water and the bubbles disappear.

Porous Venturi-Orifice Microbubble Generator for Oxygen Dissolution in Water

“…Microbubble-based processes have emerged as a promising option for enhancing interphases mass-transfer for industrial applications [1]. The application of microbubbles in the aquaculture industry helps to enhance productivity, water quality, hydroponic plant growth and soil fermentation [2]. For example, microbubble generators (MBG) have been used in the farming of oyster [3,4] for promoting growth, shell opening and the increment of oyster's blood flow rate, ascertaining the beneficial effect on the bioactivity [3].…”

“…Microbubbles are generated through three fundamental methods: pressurization dissolution (decompression), rotating-flow (spiral flow) and cavitation for ejector and/or venturi methods [10,12,13]. These basic methods are the base for most of the recent modifications and optimizations [2]. Some of the recent developments include a system based on a porous media, constant flow nozzles and membrane or gas spargers coupled with a mixer (i.e., impeller) [12].…”