Magnetic Particle Spectroscopy and Applications

Magnetic particle spectroscopy (MPS) is a powerful technique for probing the dynamic magnetization of magnetic nanoparticles (MNPs) under oscillating magnetic fields. The resulting harmonic signals provide quantitative information that enables a wide range of applications, including biological assays, viscosity measurements, and temperature sensing. In recent years, MPS has attracted increased interest for medical diagnostics due to its superior signal-to-noise ratio, operational simplicity, and lower cost relative to magnetic, electrical, and optical counterparts. In this presentation, I will discuss three recent advances from our group. First, we have developed a portable MPS platform designed for point-of-need biological testing. Second, we examine device-level and assay-level optimizations that improve sensitivity and reduce measurement time. Third, we demonstrate a strategy for multiplexed detection that enables simultaneous, cost-efficient identification of multiple pathogens—an essential capability given the overlapping symptoms of many diseases and the practical constraints of diagnostic workflows. In particular, I will highlight our recent efforts to optimize the amplitude and frequency of the excitation fields by accounting for both Néel and Brownian relaxation mechanisms, thereby maximizing signal output across diverse operational regimes. Finally, I will report on the feasibility of multiplexed MPS-based immunoassays using "magnetic colorization" of MNPs to differentiate targets, illustrating a promising path toward scalable, affordable, and high-throughput diagnostic solutions.