Research On Key Technologies Of Temperature Measurement Using Magnetic Nanoparticles

The magnetic nanoparticles thermometry,utilizing magnetic-temperature sensitivity of magnetic nanoparticles,can realize the non-invasive temperature measurement.So as to have the unique application advantage in the field of biomedicine(tumours hyperthermia,targeted drug delivery)and industrial applications(IGBT,high-power LED),etc.Although magnetic nanoparticles thermometry has many advantages compared to the traditional thermometry in the aspects of non-invasion and real-time accurate temperature measurement inside living and opaque objects,its application has many problems not solved about many key technical problems.Firstly,(1)harmonic characteristics of magnetizing response of magnetic nanoparticles is analysed under the excitation by mixed alternating magnetic field to select optimizely harmonic component with optimal signal-to-noise ratio and temperature sensitivity as its constraints to build up temperature calculation model constructed under the mixed frequency magnetic field excitation,whose model has higher measurement accuracy and wider applicable scope of temperature compared with single frequency excitation magnetic nano temperature measurement model.(2)The improved model of magnetic nano temperature measurement is put forward under the triangle wave excitation,avoiding non-conformity of magnetization response waveform phase and theoretical phase.Secondly,effect of particle size distribution on the magnetization response signal of magnetic nanoparticles is analysed aiming at the problems of particle size distribution.After that,the two major particle sizes of magnetic nanoparticle samples are creatively put forward to approximate its particle size distribution,and provide the simplified harmonic expression under two major core particle sizes.The mathematical relationship model is established between harmonic of magnetization response of magnetic nanoparticles and particle size distribution.The simulation and experimental results show that this method can fast and precisely estimate the core size distribution of magnetic nanoparticles.At the end of this thesis,(1)the magnetic nanoparticles thermometry was successfully applied to measure the temperature of chip and fluorescent layer of high-power LED,experimentally proving that fluorescent layer is also one of the main heating sources of internal LED except for chips.(2)Based on the improved magnetic nanoparticles thermometry under triangle wave excitation,the closed-loop feedback temperature control system has temperature fluctuation less than 0.5 K at the expected temperature of 315 K.The method provides a new solution for temperature measurement and feedback control in hyperthermia.