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A full-freedom wireless power transfer for spheroid joints is proposed to solve the problem of power transmission between the caput-articularis and the acetabulum in a spheroid joint. According to the characteristics of the spheroid joint, a hemispherical coil and a spherical coil are designed having no effect on the performance of the joint. Hemispherical and spherical magnetic cores are used to optimize the magnetic field distribution of the transmitter and receiver coils to reduce the electromagnetic influence on the external environment of the acetabulum and the internal environment of the caput-articularis during the power transmission process. Practical results obtained from a hardware prototype are included. They confirm that the maximum transmission efficiency of the designed system is 91%, and the transmission efficiency is always higher than 80% when the caput-articularis rotates freely. INDEX TERMS Spheroid joints, full-freedom, hemispherical coils, spherical coil, wireless power transfer (WPT).

Magnetic fluid hyperthermia (MFH) adopts the relaxation mechanism of magnetic nanoparticles to heat targeted tumors by coupling magnetic fields and temperature fields. Temperature regulation plays an important role in determining hyperthermia efficacy. It is generally difficult to obtain the distribution of temperature over the whole treatment region during clinical hyperthermia due to the limitations of invasive temperature measurements. To predict the temperature and its distribution during hyperthermia, this paper uses the finite element method and builds a coupled multiphysics model of MFH to analyze the magnetic field and temperature distributions within treated tissue and to determine the influence of the magnetic field strength on the tissue temperature during hyperthermia. The heat dissipation equations are used as inputs to determine the specific loss power of heat sources for nanoparticle injection sites. The results show the distribution of the temperature in the targeted tissue. In addition, an in vitro MFH experiment is subsequently performed with cervical cancer cell cultures. A temperature increase of approximately 4 °C is observed in the tumor tissue treated with Fe2O3 magnetic fluids when the magnetic field is applied for 30 minutes. Hence, the feasibility of hyperthermia and the accuracy of the proposed simulation model are verified with such experimental results.

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