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Open AccessArticle

Multiplex Detection of Different Magnetic Beads Using Frequency Scanning in Magnetic Frequency Mixing Technique

1
Institute of Complex Systems Bioelectronics (ICS-8), Forschungszentrum Jülich, 52425 Jülich, Germany
2
RWTH Aachen University, 52062 Aachen, Germany
*
Author to whom correspondence should be addressed.
Sensors 2019, 19(11), 2599; https://doi.org/10.3390/s19112599
Received: 14 May 2019 / Revised: 29 May 2019 / Accepted: 5 June 2019 / Published: 7 June 2019
(This article belongs to the Section Biosensors)
In modern bioanalytical methods, it is often desired to detect several targets in one sample within one measurement. Immunological methods including those that use superparamagnetic beads are an important group of techniques for these applications. The goal of this work is to investigate the feasibility of simultaneously detecting different superparamagnetic beads acting as markers using the magnetic frequency mixing technique. The frequency of the magnetic excitation field is scanned while the lower driving frequency is kept constant. Due to the particles’ nonlinear magnetization, mixing frequencies are generated. To record their amplitude and phase information, a direct digitization of the pickup-coil’s signal with subsequent Fast Fourier Transformation is performed. By synchronizing both magnetic fields, a stable phase information is gained. In this research, it is shown that the amplitude of the dominant mixing component is proportional to the amount of superparamagnetic beads inside a sample. Additionally, it is shown that the phase does not show this behaviour. Excitation frequency scans of different bead types were performed, showing different phases, without correlation to their diverse amplitudes. Two commercially available beads were selected and a determination of their amount in a mixture is performed as a demonstration for multiplex measurements. View Full-Text
Keywords: frequency mixing magnetic detection; magnetic sandwich immunoassay; multiparametric immunoassays frequency mixing magnetic detection; magnetic sandwich immunoassay; multiparametric immunoassays
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MDPI and ACS Style

Achtsnicht, S.; Pourshahidi, A.M.; Offenhäusser, A.; Krause, H.-J. Multiplex Detection of Different Magnetic Beads Using Frequency Scanning in Magnetic Frequency Mixing Technique. Sensors 2019, 19, 2599.

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