Magnetophoretic circuits for digital control of single particles and cells.

The ability to manipulate small fluid droplets, colloidal particles and single cells with the precision and parallelization of modern-day computer hardware has profound applications for biochemical detection, gene sequencing, chemical synthesis and highly parallel analysis of single cells. Drawing inspiration from general circuit theory and magnetic bubble technology, here we demonstrate a class of integrated circuits for executing sequential and parallel, timed operations on an ensemble of single particles and cells. The integrated circuits are constructed from lithographically defined, overlaid patterns of magnetic film and current lines. The magnetic patterns passively control particles similar to electrical conductors, diodes and capacitors. The current lines actively switch particles between different tracks similar to gated electrical transistors. When combined into arrays and driven by a rotating magnetic field clock, these integrated circuits have general multiplexing properties and enable the precise control of magnetizable objects

Concentric manipulation and monitoring of protein-loaded superparamagnetic cargo using magnetophoretic spider web

A lab-on-a-chip (LOC) magnetophoretic system for the remotely controllable transport of magnetic particles actuated by thin permalloy magnetic tracks has been developed as a novel architecture composed of radii and spiral tracks resembling a spider web network, where the network tracks have the asymmetric and anisotropic magnetic properties for the directional transportation of particles (cargos). A planar Hall resistance (PHR) sensor is integrated with the web networks, and the manipulation and detection are achieved via superparamagnetic particles with dual functions as a biomolecule cargo for transportation and labels for monitoring. The streptavidin protein-coated magnetic particles are precisely manipulated toward the PHR sensor surface via the radii and spiral tracks by applying an external rotating magnetic field. The stray field was analyzed in terms of the particle coverage on the sensor surface, where the sensor signal linearly varies with the number of particles on the sensor surface. This allows the effective collection of low-density biomolecule carriers to one specific point and monitors the accumulated carriers. The developed novel technology could affect multiple fields, including bioassays, cell manipulation and separation and biomechanics.1