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Coil model. a Planar litz double coils structure. b Sectional view of Planar litz double coils. c 3D wearable litz double coils structure
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Over the last decade, people paid a lot of attention to wireless magnetic resonant energy transfer system. It has become one of best method to supply power for implantable electronic devices. In this paper, a 3D wearable litz double coils (3D-WLDC) with two identical integrated flexible coils is proposed and the corresponding theoretical model for...
Citations
... However, when the horizontal offset distance between the two coils was 5 mm, the received power at the receiving coil decreased by 28%. In 2017, Chen proposed 3D wearable Litz double coils with two identical integrated flexible coils, which could be used in an implantable capsule [16]. When the transmission distance was 5 mm at the working frequency of 13.56 MHz, a power of 21.82 mW was received with the load resistance of 100 Ω. Meng presented a miniaturized implantable receiving antenna for wireless powering of a cardiac pacemaker in 2020 [17]. ...
Based on current implantable devices, a battery’s rigidity and large size makes it prone to immune rejection and wound incisions. Additionally, it is limited by its finite lifespan, which hinders long-term usage. These limitations greatly restrict the development of implantable medical device systems towards miniaturization and minimally invasive approaches. Consequently, obtaining high-fidelity and stable biological signals from the target tissue area of the organism remains challenging. Therefore, there is a need to develop wireless power transmission technology. In this paper, we propose a wireless micro energy transfer method based on MEMS micro coils for charging implantable devices. Through simulation calculations, we first investigate the influence of coaxial distance, horizontal displacement, and rotation angle between the MEMS micro coil and the transmitting coil on power transmission. Subsequently, we utilize micro nanofabrication technology to create a MEMS micro spiral copper coil with a line width, thickness, and spacing of 50 µm and a total of five turns. Finally, we conduct wireless power transmission tests on the coil. The results show that, when the transmitting coil and the receiving coil are 10 mm apart and the operating frequency is 100 kHz, the power of the wireless power transmission system reaches 45 µW. This power level is sufficient to meet the power supply requirements of implantable pacemakers. Therefore, this technology holds great potential for applications in the field of wireless power transmission for implantable medical devices, including pacemakers and brain neurostimulators.
... The mutual inductance between the coils is affected by factors such as the coil structure, relative position, and space medium. In general, the closer the distance between the coils is, the larger the coupling coefficient is, and the mutual inductance is also increased, and the transfer efficiency is further increased [39]. On the contrary, the farther the transfer distance is, the smaller the coupling coefficient is, the mutual inductance is reduced, and the efficiency is also reduced. ...
... The coupling coefficient between the two coils is increased, but the signal The mutual inductance between the coils is affected by factors such as the coil structure, relative position, and space medium. In general, the closer the distance between the coils is, the larger the coupling coefficient is, and the mutual inductance is also increased, and the transfer efficiency is further increased [39]. On the contrary, the farther the transfer distance is, the smaller the coupling coefficient is, the mutual inductance is reduced, and the efficiency is also reduced. ...
A magnetic resonance wireless power transfer system based on flexible 3D dual-coil is proposed and implemented in this paper. Firstly, a magnetic coupling resonant circuit model based on dual-coil is established, and the analysis indicates that enlarging the coil inductance and quality factor can effectively improve the transfer efficiency and performance. The coil parametric model is created by HFSS (High Frequency Structure Simulator), the effects of structural parameters on the coil inductance and quality factor are analyzed, and the optimized coil structure parameters are determined. To achieve maximum power transfer, the coupled resonant model after impedance matching is established and simulated in HFSS, and S11 reaches −30 dB at 13.56 MHz. Considering the radiation on human tissues, the SAR (Special Absorption Rate) value is evaluated simultaneously. To confirm the validity of the proposed prototype, the efficient wireless power transfer system composed of two flexible and biocompatible coils with 10 mm radius has been verified by the experimental measurements, and measure results show that the output power is 70 mW, when the transfer distance is 6 mm, the input power is 200 mW, and the maximum transfer efficiency is 35%.
Wireless power transfer (WPT) is a biocompatible and flexible, convenient and stable energy transmission technology, has a huge application market in consumer electronics and implantable medical aspects. With regard to WPT, improving the transmission efficiency has always been a great challenge. In this paper, a novel four coil wireless energy transmission system based on magnetic resonances analyzed, the formula of quality factor, transmission distance and transmission efficiency is derived. A new coil structure parameter design is proposed. Through the model simulation of the number of turns, the number of strands and the pitch of the turns, the quality factor and inductance of the coil are analyzed by the electromagnetic simulation software HFSS, and the optimal structural parameter values are obtained. The coil with the optimal structural parameters can reach 102 at 13.56 MHz frequency. These structural parameters provide effective reference and guidance for obtaining high quality factor coils and efficient wireless energy systems.
