Design Of Magnetic Nanoparticles Temperature Measurement System With Dc-SQUID

Accurate control of temperature in the cancer heat treatment is a hot topic in the field of biomedicine in recent years. Magnetic nanoparticles temperature measurement becomes a new kind of non-contact high precision temperature measurement method, because of magnetic nanoparticles temperature sensitive properties and biosecurity. This thesis, using the direct current uperconducting quantum interference device(dc-SQUID) to build a set of magnetic nanoparticles temperature measuring system, realized the non-invasive high precision temperature measurement.First of al, the two fundamental principles of measuring system are introduced. The first is the Langevin paramagnetic function model which change the magnetic nanoparticle temperature information into magnetic susceptibility. The second is the measurement principle of dc-SQUID, dc-SQUID has high sensitivity characteristics, and it can accurate measure the magnetic susceptibility and magnetic moment of magnetic nanoparticles. Also the temperature measurement model of magnetic nanoparticles are simulated, analyzed the effects of different decibels of noise on the inversion results.Then, the temperature measurement system which used to measure the magnetic nanoparticles magnetic response and temperature is designed with dc-SQUID. The excitation module ensures that the incentive sine signal amplitude stability and the frequency of a single. Measurement module detect the magnetic nanoparticle magnetic response signal into voltage signal by the tree-section coil and dc-SQUID sensors. Software module is responsible for processing the odd harmonic signal. The algorithm can eliminate the residual magnetic field, improve the accuracy of measurement.In addition, the performance of system is analyzed through the experiments. The noise and error of the measurement system is analyzed through testing the excitation magnetic field. Also the factors such as the excitation frequency, the magnetic moment of sample and the temperature of the measurement are analyzed by using the Calibration coil. It proved that the measurement system has high accuracy.Finally, the system used to measure the temperature of the magnetic nanoparticles, using the model of Langevin paramagnetic function and the algorithm of eliminating the residual magnetic field. Achieving the system which the thermometric error less than 0.1K. Show that the system can be used for the study of the magnetic properties of magnetic nanoparticles and the high precision of temperature measurement.