A fully integrated micromachined magnetic particle separator

A prototype micromachined magnetic particle separator that can separate magnetic particles from suspended liquid solutions has been realized on a silicon wafer. The requisite magnetic field gradients are generated by integrated inductive components in place of permanent magnets, which yields several advantages in design flexibility, compactness, electrical and optical monitoring, and integration feasibility (thus enabling mass production). Preliminary experiments have been performed on aqueous suspensions of magnetic beads. At 500 mA of dc current, approximately 0.03 Tesla of magnetic flux density is achieved at the gap between the quadrupoles, and the magnetic particles rapidly move toward the quadrupoles, separate from the buffer solution, and clump on the poles. The magnetic particles clumped on the poles are also easily released when the dc current is removed, achieving the primary purpose of a separator. The device shows that micromachined magnetic components have a high potential in biological or biomedical applications, especially in separating small amounts of cells or DNA that are marked with magnetic beads, especially when close monitoring and control of the process is important.