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Peter Grünberg Institute / Institute of Complex Systems

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On-chip magnetic actuation

In this project we develop a platform for on-chip magnetic actuation of magnetic particles with a resolution in the low micrometer regime. Due to their high flexibility considering surface chemistry and dimension, magnetic micro- and nanoparticles have become a versatile tool for labeling, actuation and delivery on the micron and submicron scale. The goal is to use magnetic actuation for delivery to or chemical stimulation of individual cells in lab-on-a-chip approaches.

On-chip magnetic actuation

Microwire array chips

Our chips consist of two mutually orthogonal layers of parallel microwires that are insulated from each other and from the medium. By passing current through the wires, a magnetic field is induced that can be used to attract, collect, and control magnetic micro- and nanoparticles. Functionalization of these particles with proteins, nucleic acids, or pharmaceutical compounds renders them remote controlled delivery vehicles or stimulation transducers, respectively.

Highly localized magnetic fields

Highly localized magnetic fields

When passing current through the microwires on the chip, the induced magnetic fields of each individual wire superimpose (see figure to the left). This results in highly localized peaks in the magnetic field above the activated cell of the array. Magnetic beads are attracted by regions of high field strength and can thus be trapped, concentrated and moved passing appropriate current patterns through the wire array.

Collection, actuation and control of particles

Collection, actuation and control of particles

By applying appropriate current sequences, defined clouds of magnetic microparticles can be collected on the chip. These clouds can then be moved, separated or rejoined by applying different patterns of potential differences to the individual wires. Also, using glass microcapillaries we can apply single particles to the activated trap and manipulate these while digitally tracking their position with high precision.

Additional Information


Jun.-Prof. Dr. Bernhard Wolfrum

Tel.:  +49-2461-61-3285


Philipp Rinklin, Hans-Joachim Krause and Bernhard Wolfrum: On-chip control of magnetic particles. Physica Status Solidi, 5 (2012) (front cover)


P. Rinklin, H.-J. Krause, B. Wolfrum: Actuation and tracking of a single magnetic particle on a chip. Applied Physics Letters, 100, 014107 (2012)