Electroforming of Magnetic Microtubes for Microrobotic Applications

Hard- and soft-magnetic microtubes are proposed for minimal invasive drug delivery and assistance in surgical operations. Cobalt-based alloys are electroformed on sacrificial wires and subsequently released. Cobalt-platinum (CoPt) is used as hard-magnetic material and cobalt-nickel (CoNi) as soft-magnetic. CoPt microtubes show coercivities of 160 kA/m (2 kOe) and remanence of 0.2 T. CoNi microtubes show coercivities below 1.6 kA/m (20 Oe) with a saturation magnetization above 1.3 T. The CoPt microtubes were magnetized perpendicular to their cylindrical axes, (i.e., short axis) using a 5 T magnetizer. The microtubes were tested with a custom magnetic manipulation setup and their behavior under applied fields was analyzed.