LilaG writes "Not just a way to transport trains at high speed, magnetic levitation could find use in diagnosing disease. Researchers at Harvard have shown that they can detect proteins in blood using MagLev. The researchers, led by George Whitesides, use levitation to detect a change in the density of porous gel beads that occurs when a protein binds to ligands inside the beads. The lower the bead levitates, the more protein it holds. The method (abstract of paywalled article) could work for detecting disease proteins in people's blood samples in the developing world: The magnets cost only about $5 each, and the device requires no electricity or batteries. Because the beads are visible to the naked eye, researchers can make measurements with a simple ruler with a millimeter scale."