Microelectromagnets for the manipulation of biological systems
  Microelectromagnet devices, a ring trap and a matrix, were developed for the microscopic control of biological systems. The ring trap is a circular Au wire with an insulator on top. The matrix has two arrays of straight Au wires, one array perpendicular to the other, that are separated and topped by insulating layers. Microelectromagnets can produce strong magnetic fields to stably manipulate magnetically tagged biological systems in a fluid. Moreover, by controlling the currents flowing through the wires, a microelectromagnet matrix can move a peak in the magnetic field magnitude continuously over the surface of the device, generate multiple peaks simultaneously and control them independently. These capabilities of a matrix can be used to trap, continuously transport, assemble, separate and sort biological samples on micrometer length scales. Combining microelectromagnets with microfluidic systems, chip-based experimental systems can be realized for novel applications in biological and biomedical studies. 
H. Lee, A.M. Purdon, R.M. Westervelt