TY  - JOUR
A1  - Engelmann, Ulrich M.
A1  - Simsek, Beril
A1  - Shalaby, Ahmed
A1  - Krause, Hans-Joachim
T1  - Key contributors to signal generation in frequency mixing magnetic detection (FMMD): an in silico study
JF  - Sensors
N2  - Frequency mixing magnetic detection (FMMD) is a sensitive and selective technique to detect magnetic nanoparticles (MNPs) serving as probes for binding biological targets. Its principle relies on the nonlinear magnetic relaxation dynamics of a particle ensemble interacting with a dual frequency external magnetic field. In order to increase its sensitivity, lower its limit of detection and overall improve its applicability in biosensing, matching combinations of external field parameters and internal particle properties are being sought to advance FMMD. In this study, we systematically probe the aforementioned interaction with coupled Néel–Brownian dynamic relaxation simulations to examine how key MNP properties as well as applied field parameters affect the frequency mixing signal generation. It is found that the core size of MNPs dominates their nonlinear magnetic response, with the strongest contributions from the largest particles. The drive field amplitude dominates the shape of the field-dependent response, whereas effective anisotropy and hydrodynamic size of the particles only weakly influence the signal generation in FMMD. For tailoring the MNP properties and parameters of the setup towards optimal FMMD signal generation, our findings suggest choosing large particles of core sizes dc > 25 nm nm with narrow size distributions (σ < 0.1) to minimize the required drive field amplitude. This allows potential improvements of FMMD as a stand-alone application, as well as advances in magnetic particle imaging, hyperthermia and magnetic immunoassays.
KW  - key performance indicators
KW  - magnetic biosensing
KW  - coupled Néel–Brownian relaxation dynamics
KW  - frequency mixing magnetic detection
KW  - magnetic relaxation
KW  - micromagnetic simulation
KW  - magnetic nanoparticles
Y1  - 2024
U6  - http://dx.doi.org/10.3390/s24061945
SN  - 1424-8220
N1  - This article belongs to the Special Issue "Advances in Magnetic Sensors and Their Applications"
VL  - 24
IS  - 6
PB  - MDPI
CY  - Basel
ER  -