Optimal Anti-Noise Ability and High Sensitivity in Magnetic Nanothermometry

In this study, we present a novel noninvasive and real-time magnetic nanothermometry (MNTM) using both odd and even harmonics of magnetic nanoparticles (MNPs) under low frequency (f = 117 Hz) ac and dc magnetic fields. Based on the first-order Langevin function, the mathematical models of weighted amplitude summation of odd and even harmonics of MNPs are proposed. Antinoise ability and sensitivity of MNTM determined by saturation magnetization, M
_s
, and particle diameter, D, are discussed in detail to provide guidance for the synthesis of temperature-sensing MNPs applied in different temperature ranges. We have found that the method presented in this study has better antinoise ability, and MNPs (M
_s
= 477 kA/m) with diameters of approximately 25 nm are more suitable for temperature probing in physiological temperature range. Experimental result shows that the maximum temperature measurement error of this novel method is below 0.28 K with a standard deviation of 0.09 K in 1 s measurement.