Performance demonstration of cavity-free planar multi-stage bileg and unileg silicon-nanowire thermoelectric generators.

A Thermoelectric (TE) generator is expected to play an important role in the operation of tiny-watt capable wireless power supply devices by converting the waste heat energy into electrical energy. This work is the demonstration of planar cavity-free multi-stage n-type unileg- and bileg Si-nanowire (Si-NW) TE generators. The result shows that the output power of the multi-stage bileg-TE generator increases linearly with increasing the stage number, whereas the rate of increase of the multi-stage unileg-TE generator power output tends to decrease as the stage number increases. Although the power of the multi-stage bileg-TE generator fabricated in this work was smaller than that of the multi-stage unileg-TE generator due to the large internal resistance of p-type elements, however, the improved linearity of the bileg-TE generator than the unileg-TE generator indicates the potential advantage of the multi-stage bileg-TE generator for the large-scale integration.

Circularly polarized RF coil for energy harvesting in clinical MRI

Radiofrequency (RF) harvesting is a promising technology for the wireless power supply of various in-bore devices used in magnetic resonance imaging. However, current technical solutions in this area are based on the conversion of linearly polarized RF fields, and thus their efficiency is limited, as they interact only with a fraction of circularly polarized RF fields. In the present work, we introduce and experimentally realize a novel harvesting setup allowing for converting circularly polarized RF fields to direct current.

Вплив енерговтрат імплантата з бездротовим живленням на тепловий стан організму

Technical means that create for regenerating lost functions of the human body primarily focused on the target function. However, even when implants achieve performance that corresponds to natural organs and systems, in many cases the developers do not pay enough attention to the energy supply of implants and additional heat load due to energy losses in mechanical, electrical, and electronic units. If you do not consider these factors, it limits the duration and medical safety of the devices. It is especially true for implants with significant power consumption and wireless power supply. Therefore, this work determines the allowable additional heat load of the human body to justify the choice of further circuit solutions for wireless powering of implants with significant energy consumption and long-term operation. The subject of research is the processes of heat exchange between the implant and body structures and their energy and temperature indicators. The research object was chosen as an implant of the type "Artificial Heart" device (AHD) with a maximum power of 20… 25 W and the magnetic induction principle of energy transfer. The research tasks are to analyze the processes of heat exchange between the implant and the biostructures of the body; to calculate quantitative indicators of energy exchange in the location of the main components of the implant; to determine the temperature of biotissues in the area of the receiving inductor. The subject of research is the processes of heat exchange between the implant and body structures and their energy and temperature indicators. The research object was chosen as the implant of the type "Artificial Heart" device (AHD) with a maximum power of 20… 25 W and the magnetic induction principle of energy transfer. The research tasks are to analyze the processes of heat exchange between the implant and the biostructures of the body; to calculate quantitative indicators of energy exchange in the location of the main components of the implant; to determine the temperature of biotissues in the area of the receiving inductor. Research results. The processes of heat exchange between the structural elements of the implant and the biostructures of the body have a complex combination of physiological and physical mechanisms. Estimates are made based on the thermal conductivity process, as the most objective in terms of known quantitative indicators. With an average efficiency of ~ 0.8 for mechanical, electrical, and electronic components of the implant "Artificial Heart," the human body can maintain a stable temperature of internal organs in the presence of an implant with a maximum power consumption of 20 watts. The calculation conducted using the method of electrothermal analogy showed a possible increase in the temperature of biotissues in contact with the surface of the receiving implanted inductor, by 1.32 ° C. This value refers to the critical levels of internal tissue temperature rise. Summary. For practical implementation of the autonomous device the Artificial Heart Device, it is necessary to combine known or to find the original circuit-technical and design decisions of construction of components of wireless power supply with the magnetic induction principle and efficiency of not less than 0,8. To prevent thermal overload of biotissues, it is advisable to introduce a temperature control channel at potentially critical locations of the implanted elements. It is possible to predict the finding of these critical points by calculations by the method of electrothermal analogy.

Research on Desktop Wide Range Wireless Power Transfer Based on High Frequency Electric Field

This paper proposes a desktop wireless power transfer system that can wirelessly supply power to electrical equipment in a certain space above the aluminum foil using only a high-frequency electric field. Compared with other wireless power supply systems, this system has a smaller power receiving device and a wider power supply range, which is convenient for wireless power supply of portable electrical equipment and low-power electric vehicles. The power receiving device of the system is only the size of a mobile phone, and the power supply range can reach 1.2 m2. This article introduces the system design, electromagnetic field simulation and experiment of the desktop wireless power transfer system. The experimental results show that by using a mobile phone-sized receiving device to connect a light bulb and a fan, multiple loads can simultaneously receive power in a specific space above the desktop power supply. In addition, people can hold the power receiving device for wireless charging.