Wireless power transfer systems are increasingly used as a means of charging implantable medical devices. However, the heat or thermal radiation from the wireless power transfer system can be harmful to biological tissue. In this research, we designed and implemented a wireless power transfer system-based implantable medical device with low thermal radiation, achieving 44.5% coil-to-coil efficiency. To suppress thermal radiation from the transmitting coil during charging, we minimized the ESR value of the transmitting coil. To increase power transfer efficiency, a ferrite film was applied on the receiving part. Based on analyses, we fabricated a cardiac monitoring system with dimensions of 17 × 24 × 8 mm 3 and implanted it in a rat. We confirmed that the temperature of the wireless charging device increased by only 2 • C during the 70 min charging, which makes it safe enough to use as an implantable medical device charging system.

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The current 15-month coronavirus disease-19 (COVID-19) pandemic caused by SARS-CoV-2 has accounted for 3.77 million deaths and enormous worldwide social and economic losses. A high volume of vaccine production is urgently required to eliminate COVID-19. Inexpensive and robust production platforms will improve the distribution of vaccines to resource-limited countries. Plant species offer such platforms, particularly through the production of recombinant proteins to serve as immunogens. To achieve this goal, here we expressed the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein in the glycoengineered-tobacco plant Nicotiana benthamiana to provide a candidate subunit vaccine. This recombinant RBD elicited humoral immunity in mice via induction of highly neutralizing antibodies. These findings provide a strong foundation to further advance the development of plant-expressed RBD antigens for use as an effective, safe, and inexpensive SARS-CoV-2 vaccine. Moreover, our study further highlights the utility of plant species for vaccine development.

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Abstract Recently, a wireless charging system (WCS) for drones has been extensively studied, although standards for compliance testing of a WCS for drones have yet to be established. In this study, we propose methods for human exposure assessments of a WCS for drones by comprehensively considering the various positions of the system and the postures of human body models. The electromagnetic fields from a WCS are modeled and the internal quantities of the human body models, consisting of current density, internal electric field and specific absorption rate, are calculated. The incident fields around the WCS and the internal quantities are analyzed at 140 kHz, which is the operating frequency of the WCS applied. Results of an exposure assessment based on the confirmed worst-case scenario are presented. In addition, the internal quantities depending on the human body models and the material characteristics of the simplified models are also discussed using four different anatomical and simplified human body models.

This paper analyzes how over-coupled coils affect odd harmonic current and electromagnetic interference (EMI) in a wireless power transfer (WPT) system, and proposes design considerations for series inductors to solve the EMI problem. When the air gap of the coils of the WPT system decreases below a certain level and the coils are over-coupled, the odd harmonic component of the input impedance of the system decreases and odd harmonic currents increase. The increase in the odd harmonic components current quickly aggravates the EMI issues. To solve the EMI problem of the over-coupled WPT system, additional series inductors were applied to the system, and considerations for designing the series inductors were analyzed. When designing additional series inductors, power transfer efficiency, maximum power transfer, input impedance and odd harmonic components current must be considered. Using simulations and experiments, it was confirmed that the WPT system designed with analyzed considerations maintained relatively high efficiency and reduced EMI issues.

Recently, maintenance applications around power lines have been actively studied. These applications usually supply power through magnetic energy harvesting(MEH) to devices around the power line. A major challenge for practical MEH is to overcome magnetic saturation, which can cause degradation of power density under a wide current range in the power line. In this paper, we propose a design methodology to harvest maximized output power by considering the saturation effect. To consider magnetic saturation, the output power model and the saturable magnetizing inductance model based on magnetizing current were comprehensively analyzed. Additionally, the critical point of saturation for the maximum harvested power was analyzed by considering different primary side current conditions. With the proposed design methodology, the accuracy and efficiency of the output model were verified with experimental results compared to the conventional model. To consider the real environment, a 150 kW class of AC resistor load bank was implemented to control the primary current from 0 to 100 A with power frequency of 60 Hz. Experimental results show that the proposed method can harvest an average power of 14.32 W on 70 A power line, which is an increase of 39.8 % compared with the conventional design method.