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.
@article{doi:10.17170/kobra-2024042410064,
author ={Huhnstock, Rico and Paetzold, Lukas and Merkel, Maximilian and Kuświk, Piotr and Ehresmann, Arno},
title ={Combined Funnel, Concentrator, and Particle Valve Functional Element for Magnetophoretic Bead Transport Based on Engineered Magnetic Domain Patterns},
keywords ={530 and Lab on a Chip and Teilchen and Magnetpartikelbildgebung and Magnetfeld},
copyright ={http://creativecommons.org/licenses/by/4.0/},
language ={en},
journal ={Small : nano micro},
year ={2023-10-27}
}