Fabrication of three-dimensional magnetic microdevices with embedded microcoils for magnetic potential concentration

Novel magnetic microdevices were developed for magnetic field generation and concentration and successfully characterized and tested for magnetic potential focusing which is very important for various MEMS applications such as magnetic particles manipulation. These microdevices have been fabricated using an innovative processing sequence which eliminates many problems associated with other fabrication techniques and provides a platform for adding other subsequent fabrication steps required to integrate the microcoils with other microcomponents. They consist of high aspect ratio planar coils made of electroplated copper embedded in the silicon substrate, with ferromagnetic pillars and backside plates made of a CoNiP ternary alloy. A large magnetic field gradient is generated and enhanced by two structural parameters: the small width and high aspect ratio of each single conductor and the ferromagnetic pillars positioned at high flux density locations. This arrangement creates very steep magnetic potential wells, in particular at the vicinity of the pillars. The manipulation of micromagnetic particles in a static and continuous flow conditions has been demonstrated.