A Systematic Measurement Study of Magnetoresistance Sensor Selection and Differential Configuration for Magnetic Nanoparticle Quantification
Year: 2026
Type: article
Abstract: Magnetic nanoparticles (MNPs) are widely used in biomagnetic sensing and bioassays, where accurate and reliable concentration quantification is often required. Relaxation-based magnetic detection exploits the nonlinear magnetization dynamics of MNPs and is commonly employed to probe particle mobility and bio-binding effects; under controlled excitation, the harmonic magnetic response can also be used for concentration measurement. Usually, the pickup element consists of a wound coil collinearly aligned with the excitation source. While conventional multiturn coil-based magnetic particle spectroscopy (MPS) detection offers high sensitivity, its geometry can constrain flowthrough or continuous liquid-phase measurements. In this work, we present a systematic experimental evaluation of giant magnetoresistance (GMR) and tunnel magnetoresistance (TMR) sensors evaluated in three different measurement configurations: single, differential horizontal, and differential vertical. The setup is operated in an anti-Helmholtz configuration. Multiple commercially available magnetoresistance (MR) sensors with different intrinsic sensitivities and dynamic ranges were investigated under a unified excitation, conditioning, and lock-in processing framework. Measurement performances were assessed via concentration-sweep experiments of a 100-nm MNP dilution series by calculating sensitivity, linearity, signal-to-noise ratio (SNR), and repeatability quantified by the coefficient of variation (CV). As a signal, the first, third, and fifth harmonics were analyzed, where the first harmonic amplitude and phase change provided the most robust and monotonic concentration dependence and was therefore used for performance comparison. The results demonstrate sensorlevel tradeoffs between intrinsic responsivity, usable dynamic range, and measurement uncertainty, while vertical differential pairing consistently improves detectability relative to horizontal configuration within the anti-Helmholtz geometry. The presented framework provides practical guidance for the design and integration of MR sensors in compact relaxation-based biomagnetic sensing systems.
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,645
OpenAlex ID: W7221174667