Fabrication and characterization of polymer membranes with integrated arrays of high performance micro-magnets

Micro-fabrication techniques (lithography, deep reactive ion etching and sputtering) have been used to prepare regular arrays of micro-magnets on the surface of topographically patterned Si substrates. These arrays, composed of either high magnetization soft magnetic Fe65Co35 or high coercivity hard magnetic Nd–Fe–B, were embedded in a polymer matrix of polydimethylsiloxane which could be mechanically peeled off the Si substrate to produce free standing magnetic membranes. Scanning Hall probe microscopy was used to measure the stray field patterns produced at distances in the range of 10–50μm above the membranes. The level of control achieved over the shape, size and spatial distribution of the hard or soft magnetic elements, combined with the transparency, flexibility and biocompatibility of the polymer matrix, renders the composite membranes attractive for use in micro-systems in general and bio-micro-systems in particular.