Related Experiment Video
Updated: Jul 12, 2025

A Paired Bead and Magnet Array for Molding Microwells with Variable Concave Geometries
Published on: January 28, 2018
Combined Funnel, Concentrator, and Particle Valve Functional Element for Magnetophoretic Bead Transport Based on
Rico Huhnstock1,2, Lukas Paetzold1,2, Maximilian Merkel1,2
1Institute of Physics and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel, Heinrich-Plett-Str. 40, D-34132, Kassel, Germany.
Abstract:
Controlled actuation of superparamagnetic beads (SPBs) within a microfluidic environment using tailored dynamic magnetic field landscapes (MFLs) is a potent approach for the realization of point-of-care diagnostics within Lab-on-a-chip (LOC) systems. Making use of an engineered magnetic domain pattern as the MFL source, a functional LOC-element with combined magnetophoretic "funnel", concentrator, and "valve" functions for micron-sized SPBs is presented. A parallel-stripe domain pattern design with periodically decreasing/increasing stripe lengths is fabricated in a topographically flat continuous exchange biased (EB) thin film system by ion bombardment induced magnetic patterning (IBMP). It is demonstrated that, upon application of external magnetic field pulses, a fully reversible concentration of SPBs at the domain pattern's focal point occurs. In addition, it is shown that this functionality may be used as an SPB "funnel", allowing only a maximum number of particles to pass through the focal point. Adjusting the pulse time length, the focal point can be clogged up for incoming SPBs, resembling an on/off switchable particle "valve". The observations are supported by quantitative theoretical force considerations.
Related Concept Videos
Other Unique Bacteria
Ferromagnetism
Magnetism
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...

