Manipulation of magnetic microbeads in suspension using micromagnetic systems fabricated with soft lithography

Current-carrying microcircuits can generate strong magnetic-field gradients; these gradients, in turn, can control the position of magnetic microbeads in aqueous suspension. Micromagnetic systems were prepared using two representative soft lithography techniques-micromolding in capillaries and microtransfer molding-combined with electrodeposition. They can capture microbeads from solution, hold them in a fixed position, and move them along complex paths. Simply changing the current flowing in the systems can dynamically reconfigure the paths. The manipulation of magnetic microbeads using microfabricated circuits should expand current sample handling capabilities for biotechnology and combinational technology with or without the presence of net fluid flow and microfluidic channels. (C) 2001 American Institute of Physics.