Design of high-accuracy alternating magnetic field generator in magnetic nanoparticle nanothermometer

The accurate and real-time temperature is a key factor in tumor hyperthermia. In practical applications, the homogeneity of the magnetic field will affect the measurement accuracy of the magnetic nanoparticle thermometer. In this work, we explored the relationship between temperature error and magnetic field homogeneity. The condition for the measurement error of the magnetic nanoparticle nanothermometer to reach 0.1K is that the magnetic field homogeneity must be less than 0.01%. We analyzed the range of the uniform magnetic field of the Helmholtz coil with the homogeneity of 0.01%. In order to reduce the error in sample placement, we expect to vary some influencing factors, such as the number of coils and the position and size of the coil structure, in order to obtain the best results. A comparison of the range of uniform magnetic fields generated by the Helmholtz coil and the three-coil improved coil shows that the improved three-coil coil can generate a uniform magnetic field with the homogeneity less than 0.01% in 45% of the symmetric magnetic field space, which is about twice that of the Helmholtz coil. In the sample position, the range is expanded from 1×10
^-6
R to within 0.021 R, which increases the range of the sample placement area and reduces the error caused by sample placement. The magnetic field generator based on three coils can maximize the uniform magnetic field area and expand the range of sample placement area, which can provide an excellent foundation for the accurate measuring of the magnetic nanoparticle nanothermometer.