Low-friction Glass Encased Magnetic Stir Bars

摘要

Magnetic stir bars encased in glass, rather than Teflon, provide the ability to rapidly mix solutions that are sensitive to contamination by organic matter and trace gases. However, the magnets of commercially available stir bars are tightly encased in simple glass cylinders that suffer from i) extensive frictional grinding during use, and ii) fracturing at high temperatures due to differences in the coefficients of thermal expansion of the magnet and the glass. To overcome these deficiencies, a novel low-friction stir bar was created by loosely encasing the magnet in a Pyrex tube with two solid glass pivot rings near its center.