Microwave processing of materials has been found to deliver enormous advantages over conventional processing methods in terms of mechanical and physical properties of the materials. However, the non-uniform temperature distribution is the key problem of microwave processing, which is related to the structure of the cavity, and the placement and physical parameters of the material. In this paper, a new microwave cavity structure with a sliding short based on phase-shifting heating is creatively proposed to improve the temperature uniformity. An electronic mathematical model based on the Finite Element Method (FEM) is built to predict the temperature distribution. Meanwhile, a new computational approach based on the theory of transformation optics is first provided to solve the problem of the moving boundary in the model simulation. At first, the experiment is carried out to validate the model, and heating results from the experiment show good agreement with the model’s prediction. Based on the verified model, materials selected among a wide range of dielectric constants are treated by stationary heating and phase-shifting heating. The coefficient of variation (COV) of the temperature and temperature difference has been compared in detail between stationary heating and phase-shifting heating. A significant improvement in heating uniformity can be seen from the temperature distribution for most of the materials. Furthermore, three other materials are also treated at high temperature and the heating uniformity is also improved. Briefly, the strategy of phase-shifting heating plays a significant role in solve the problem of non-uniform heating in microwave-based material processing. A 25%–58% increase in uniformity from adapting the phase-shifting method can be observed for the microwave-processed materials.

In this article, we propose a novel metasurface-basedmagnetic coupling resonant wireless power transfer (MCR-WPT) system to realize planar omnidirectional WPT at a mid-range distance. The resonator devices—dielectric-constant disks or planar helixes—are located on both sides of the metasurface, which comprises conducting wires placed in a planar sunburst pattern. Transmission efficiency of >40% is achieved on a circular plane with a diameter of ∼40 cm. In addition, the transfer efficiency is insensitive to the placement of a human hand near the proposed MCR-WPT system. The maximum permissible input powers for the coil and dielectric resonator versions of the proposed MCR-WPT system are 0.83 and 2.56 W, respectively, in compliance with the limit prescribed in the International Commission of Non-Ionizing Radiation Protection guidelines. The proposed design may help realize many potential WPT applications, especially for the desktop wireless charging of household devices, such as mobile phones, tablets, and LED desk lamps.

The transmitting and receiving coils used in wireless power transfer (WPT) systems in electric vehicles (EVs) have a larger air gap (~300 mm) and higher transmission power (kW) than those in typical WPT systems used in electrical appliances. However, this could weaken the magnetic field, reduce transfer efficiency, and lead to a public concern regarding potential adverse health effects related to electromagnetic field (EMF) exposure. Therefore, the assessment of compliance with product safety standards, based on international exposure guidelines such as the International Commission on Non-Ionizing Radiation Protection (ICNIRP), is crucial. This study uses the finite element method to analyze a commonly used core-less and core-based WPT system using a composite core material in EVs and scalar potential finite difference method for assessment of human protection. Based on the computational results, two core structures using different types of intermediate insert blocks were analyzed to reduce external magnetic fields and mitigate the human EMF exposure. The WPT system with a core structure improved the transfer efficiency by 34% for a 300 mm air gap over the core-less system. Moreover, this effectively reduced magnetic field leakage by 91.6% and induced electric field by 98.3%, resulting in the reduction of induced electric field in anatomical human body model. The results demonstrated that a WPT system with a composite core can simultaneously improve the transfer efficiency and protect humans from EMF exposure.

Wireless power transfer (WPT) technology offers a promising solution for overcoming the power capacity limitation of implanted medical devices (IMDs). The stability in power transfer efficiency and the distance coverage of this technology both need to be improved, however. Furthermore, patient experience is frequently disregarded in current designs. Thus, this study proposes a novel inductively coupled WPT (ICWPT) system for human torso IMDs in any position and orientation. In this proposal, a “four-leg track” type coil and a modified Helmholtz coil comprise the transmitter to excite a nonzero uniform magnetic field for all components of the Cartesian axes over the torso. In addition, a single-axis coil serving as the receiver is connected to a novel I-type ferrite core. Computational results demonstrate that the power transfer efficiency improves to 1.1%–3.4% with a volume of 0.2 $\times$ 0.2 $\times$ 0.1 m in the torso, leading to improvements in power transfer stability and spatial coverage compared with the previous design (0.48%–3.2%). These improvements are also due to an impressive relative increment in quality factor of 37.3% for the innovative receiver, achieved without any increase in size. Moreover, the difference in charging coverage exceeds 50% when the minimum power transfer efficiency criterion surpasses 2% compared to the previous design. By complying with the limits of the IEEE C95.1 standard and the guidelines of the International Commission of Non-Ionizing Radiation Protection (ICNIRP), the maximal permissible transmitted power can reach up to 904 mW, which satisfies the power requirements of the majority of IMDs used in present clinical practice. The proposed ICWPT system could simplify some IMDs applications, particularly for upcoming multifunctional capsule robots with active motion control. Furthermore, the compact design of the transmitter would effectively improve patient comfort. To validate the computational results, an experiment was demonstrated.

The recent advances in computational dosimetry for electromagnetics and thermodynamics are reviewed to assess human exposure to electromagnetic fields in the MHz-to-terahertz range. This review emphasizes model variability in computational dosimetry. Apart from computational electromagnetic methods and their usage, the developments in anatomical phantoms and tissue dielectric properties characterization are also surveyed. In addition, the rationale for dosimetric quantities prescribed in international exposure guidelines, such as the specific absorption rate (SAR) and absorbed power density, is revisited in relation to their correlation with local and core temperature rises in various tissues and populations. A heating factor, which is defined as a steady-state temperature rise per SAR, for the brain, eye lens, skin, and body core is evaluated to estimate heating resulting from exposure to electromagnetic fields. The transition of a physical quantity in the guidelines at 6 GHz, from SAR to the absorbed power density, is discussed along with the optimal spatial averaging volume and areas. Computational evaluations of product compliance, 5G devices, and wireless power transfer systems are also reviewed. This review aims to synthesize the current knowledge, identify key sources of computational model variability and uncertainty, and outline further research needs for setting exposure guidelines and compliance assessment.

Wireless power transfer (WPT) technologies are increasingly being applied in fields ranging from consumer electronics and electric vehicles to space-based energy systems and medical implants. While WPT offers contactless power delivery, it introduces electromagnetic field (EMF) exposures, necessitating careful assessment to address safety and public health concerns. Exposure guidelines developed by ICNIRP and IEEE define frequency-dependent limits based on internal quantities, such as electric field strength and specific absorption rate, intended to prevent tissue nerve stimulation < 100 kHz and heating > 100 kHz, respectively. Complementing these guidelines, assessment standards such as the International Electrotechnical Commission (IEC)/IEEE 63184 and IEC Technical Report 63377, provide practical procedures for evaluating the EMF exposure from WPT systems. This review provides a comparative overview of major WPT modalities, focusing on recent developments in computational dosimetry and standardized assessment techniques for the complex, non-uniform fields inherent in WPT environments. It also addresses electromagnetic interference with medical devices and exposure scenarios involving partial-body proximity and various postures. A notable observation across modalities is the considerable variability, often spanning an order of magnitude, in the allowable transfer power, depending on the field distribution and assessment approach. Remaining challenges include the lack of harmonized guidance for intermediate frequencies and localized exposure, underscoring the importance of further coordination in international standardization efforts. Addressing these issues is critical to ensuring the safe and widespread deployment of WPT technologies.