The Dynalon micro (flea) round stir bar has a white PTFE casing and an internal magnet made from alnico V (an alloy of aluminum, nickel, iron, and cobalt) for low-volume laboratory stirring applications. The round, cylindrical shape provides better centering and creates less turbulence than a multisided shape. The magnet sits inside a polytetrafluoroethylene (PTFE) casing, which is chemically inert, can be used with corrosive chemicals, and helps reduce friction and wear while spinning. The bar's smooth surface provides quicker cleanup and less risk of cross-contamination than bars with pivot rings and allows the bar to spin on the bottom of the container for dispersing light sediment and air bubbles. This micro stir bar (also called a flea) is for stirring small volumes of liquid in containers such as test tubes, vials, and gradients.
Magnetic stir bars (sometimes called stirring bars, spin bars, or fleas) are used to stir a liquid or solution in biological, chemical, medical, and research laboratory applications. The stir bar is placed inside a container of liquid or solution that is seated on a magnetic stirrer (also called a magnetic mixer), which is a laboratory device that creates a rotating magnetic field using a rotating magnet or multiple stationary electromagnets. The rotating magnetic field causes the bar to spin, which stirs the liquid or solution. Stirring bars are offered in a variety of sizes and shapes, and they are encased in materials such as glass or plastic to help prevent contamination of the liquid or solution, to reduce friction, and to provide resistance to chemicals, abrasion, and heat. The bar may have a pivot ring or pivot point to minimize contact with the container, reduce friction, and improve its spinning. The size and shape of the container and the volume and viscosity of the liquid or solution to be stirred determine which stir bar shape, size, and casing will suit a particular application.
Dynalon manufactures plastic labware and supplies under brands such as Cowie, Kartell, and Sterilin. The company, founded in 1957, is headquartered in Rochester, NY.