Translatory and rotatory motion of Exchange-Bias capped Janus particles controlled by dynamic magnetic field landscapes

TL;DR

This study investigates how magnetic Janus particles can be precisely controlled in motion and rotation using dynamic magnetic field landscapes, enhancing their potential for lab-on-a-chip applications.

Contribution

It demonstrates the ability to steer and rotate magnetic Janus particles via tailored magnetic field sequences, revealing new control mechanisms for micro-scale particle manipulation.

Findings

Directed particle transport achieved with magnetic field landscapes.

Particle rotation can be selectively induced by adjusting pulse frequency.

Separation of translatory and rotatory motions observed under different conditions.

Abstract

Magnetic Janus particles (MJPs), fabricated by covering a non-magnetic spherical particle with a hemispherical magnetic in-plane exchange-bias layer system cap, display an onion magnetization state for comparably large diameters of a few microns. In this work, the motion characteristics of these MJPs will be investigated when they are steered by a magnetic field landscape over prototypical parallel-stripe domains, dynamically varied by superposed external magnetic field pulse sequences, in an aqueous medium. We demonstrate, that due to the engineered magnetization state in the hemispherical cap, a comparably fast, directed particle transport and particle rotation can be induced. Additionally, by modifying the frequency of the applied pulse sequence and the strengths of the individual field components, we observe a possible separation between a combined or an individual occurrence of these two types of motion. Our findings bear importance for lab-on-a-chip systems, where particle immobilization on a surface via analyte bridges shall be used for low concentration analyte detection and a particle rotation over a defined position of a substrate may dramatically increase the immobilization (and therefore analyte detection) probability.