Diamagnetic levitation with permanent magnet microarrays for precise contactless guiding and trapping of micro-droplets and bioparticles in fluids

The levitation of microdroplets of about 30 mum in diameter was achieved inside 100-mum wide trenches machined by electroerosion in permanent magnets. A low-cost mass production technique with thick permanent micromagnets electroplated above silicon was also implemented into various matrix configurations. The devices were tested with diamagnetic latex microbeads of mean diameter 3 mum in a paramagnetic buffered solution. Trapping and arraying of microparticles in stable spatial levitation within magnetic wells were successfully achieved. Contactless passive levitation brings amazing possibilities to bio-chips, including fast arraying of unlabelled cells or microbeads on micromagnets, and contamination-free biochemical micro-reactors.