AUTHORS:

Cui X., Dai Q., Chwiej J., Buczyński R., Liu W.

ABSTRACT:

Temperature is a key physical quantity that reflects the state of an organism and regulates life activities. It is of great value in magnetic hyperthermia therapy for tumors, targeted therapy, and cell dynamics research. However, existing nanotemperature measurement technologies, such as fluorescence methods, are susceptible to tissue background interference, making it difficult to achieve high-precision and repeatable in vivo temperature detection. This article proposes a high-precision temperature measurement method based on the nonlinear magnetization response of magnetic nanoparticles (MNPs). By solving the Fokker–Planck equation (FPE) and further introducing magnetic dipole–dipole interactions to correct the third harmonic phase lag, an inversion model from phase lag to temperature was established. The experiment used a 2-D rotating magnetic field (RMF) excitation and a tunnel magnetoresistive (TMR) sensor detection system to measure the third harmonic phase and determine the temperature of MNPs. In the range of 303–313 K, the maximum error was 0.36 K, and the minimum root-mean-square error (RMSE) was 0.13 K. This study provides a reliable theoretical and experimental basis for nanoscale temperature detection in high-concentration, nonuniform distribution environments.

IEEE Transactions on Instrumentation and Measurement, 2026, vol. 75, art. 6004407, doi: 10.1109/TIM.2026.3709416