| The study of precision non-invasive temperature measurement methods is of great significance in the field of biomedicine,and the temperature measurement method with magnetic nanoparticles(MNPs)is expected to achieve this goal.Based on the temperature-sensitive properties of MNPs,this thesis studies a new model of temperature measurement with MNPs under dual-frequency excitation magnetic field.And a temperature measurement system was designed to realize the precision non-invasive temperature measurement under dual-frequency excitation magnetic field.The main content is as follows.Firstly,by reference to the model of temperature measurement with MNPs under single frequency excitation magnetic field,this thesis analyzes the magnetization signal of the MNPs under the dual-frequency excitation magnetic field and summarizes the characteristics of the magnetization signal harmonics.Then,the model of temperature measurement with MNPs under dual-frequency excitation magnetic field is deduced.And the feasibility of the temperature measurement with MNPs under the dual-frequency excitation magnetic field is verified by simulation experiments.Secondly,in order to further study the temperature measurement model under dual-frequency excitation magnetic field,the influence of truncation error,signal to noise ratio(SNR)and excitation frequency on the temperature measurement accuracy is studied.To reduce the temperature error,the fifth-order truncation is determined as the final choice of the model of temperature measurement with MNPs under the dual-frequency excitation magnetic field.And,to improve the temperature measurement accuracy,it is clear that SNR should be improved as much as possible during the measurement.After that,the frequency of dual-frequency excitation magnetic field is studied by simulation,and it is shown that the frequency of dual-frequency excitation magnetic field has no significant influence on the temperature measurement error in the frequency of tens to hundreds Hz.Finally,a temperature measurement system with MNPs under dual-frequency excitation magnetic field was designed.The requirements and methods of generating the excitation magnetic field are introduced in detail.And,this thesis explains how to design the detection device of the magnetization signal,so as to minimize the effect of remanence on the temperature measurement.Then,the LABVIEW software platform and software algorithms are briefly introduced.In conclusion,temperature measurement with MNPs under dual-frequency excitation magnetic field has been realized on this system,with a temperature measurement error about 0.1K. |
