Design of a temperature measurement and feedback control system based on an improved magnetic nanoparticle thermometer

Abstract

Magnetic fluid hyperthermia, as a novel cancer treatment, requires precise temperature control at 315 K–319 K (42 °C–46 °C). However, the traditional temperature measurement method cannot obtain the real-time temperature in vivo, resulting in a lack of temperature feedback during the heating process. In this study, the feasibility of temperature measurement and feedback control using magnetic nanoparticles is proposed and demonstrated. This technique could be applied in hyperthermia. Specifically, the triangular-wave temperature measurement method is improved by reconstructing the original magnetization response of magnetic nanoparticles based on a digital phase-sensitive detection algorithm. The standard deviation of the temperature in the magnetic nanoparticle thermometer is about 0.1256 K. In experiments, the temperature fluctuation of the temperature measurement and feedback control system using magnetic nanoparticles is less than 0.5 K at the expected temperature of 315 K. This shows the feasibility of the temperature measurement method for temperature control. The method provides a new solution for temperature measurement and feedback control in hyperthermia.

Empirical Expression for AC Magnetization Harmonics of Magnetic Nanoparticles under High-Frequency Excitation Field for Thermometry

“…Liu et al [ 14 ] investigated a theoretical model of MNP temperature measurement under a DC magnetic field, which laid the foundation for developing MNP temperature measurement technology. In previous work [ 17 ], we proposed and demonstrated a temperature measurement and control system using MNPs that achieved an error of less than 0.5 K at a target temperature of 315 K, showing the feasibility of the method. However, the frequency of the excitation field heating the MNPs reached 20 kHz.…”

“…The magnetic nanoparticle thermometer (MNPT) [ 12 , 13 , 14 , 15 , 16 , 17 ] is a new tool that non-invasively measures temperature using the temperature dependency of the nonlinear magnetization of MNPs. J.B. Weaver et al [ 12 , 13 ] experimentally validated the nonlinearity of the magnetization curve and used a fitted parameter to estimate the temperature.…”

Empirical expression for harmonics of AC magnetization of magnetic nanoparticles with core size distribution

“…Weaver et al 3) proposed a new method for measuring temperature using the ratio of the 5th and 3rd harmonics of MNP magnetization, with temperature accuracy up to 0.3 K. Liu et al developed some temperature measurement methods based on MNPs under AC or a triangle magnetic field. 5,[9][10][11][12] The temperature error was less than 0.1 K with a range of 310-320 K.…”

An Improved Method for Estimating Core Size Distributions of Magnetic Nanoparticles via Magnetization Harmonics

“…The magnetization of MNPs exposed to a low-frequency AC excitation field, H ac = H sin( ωt ), can be described by the Langevin function [ 12 , 17 , 18 , 19 ]. Here, H is the amplitude of AC excitation field, w = 2 πf is the angular frequency, and f is the frequency of the AC excitation field.…”