Devices used in healthcare applications frequently require powering. With the rapid development of implantable devices for disease treatment, as well as smart digital devices dedicated for healthcare operations, wireless charging of these systems is critical. The majority of wireless powering currently uses electromagnetic fields. This work describes the in vivo demonstration of Ultrasound Power Delivery (UPD) for charging Li-ion batteries, adequate for a gastro-esophageal junction (GEJ) neurostimulator device, while fulfilling the charging module's space budget of 1.2 cc. Using the same 1 - 3 MHz UPD approach, this work describes the feasibility of charging batteries for smart devices intended for dedicated applications in a healthcare environment, with similar specifications as the wireless Qi-standard version 1.0.
The design of a rectenna system for practical use is outlined in detail. The system is physically small ($24 \times 20 \times 3 mm^{3}$) and is shielded by a ground plane from electronics behind. First experimental results are shown, using Direct Antenna Modulation, for combining power and data transfer using an information bandwidth that is wider than the antenna bandwidth.
In wireless power transfer system, a leakage electromagnetic field (EMF) that can affect a human body or peripheral devices is one of the most important problems along with system efficiency. Since ferrite and aluminum which are basically used to reduce the EMF have a high weight and cost, various studies to cancel the EMF using reverse magnetic field by additional coil are being conducted. In this paper, a reactive shield coil that can be applied to a wireless charger with multiple transmitter coils is proposed. The EMF is reduced by applying the proposed coil up to 85%.
The measurement of a microwave beam focus location was performed to validate theoretical results obtained previously using the quasioptical framework. The system in question is a preliminary set-up of a double reflector system designed for wireless power transfer studies. A very approximate value was achieved but the slight differences verified must be taken into account for the complete system experiment.
This work presents the theoretical and numerical design of a novel radiative near-field wireless power transfer (WPT) system at millimeter waves (mm-waves), based on one TX and one RX resonant Bessel-beam launcher, with the aim of providing superior performance in terms of energy focusing capabilities. To evaluate the achievable rectified power, for several TX-RX distances, the wireless link is accurately and efficiently accounted for, by combining the EM analysis of the launchers with EM theory. A single-diode rectifier is designed to operate at 37.5 GHz: for a received power of 0 dBm the expected rectifier efficiency exceeds 30%. Radiative near-field wireless power transfer (WPT) promises several benefits over both nonradiative near-field and radiative far-field wireless links. The compact size of the proposed system makes it particularly attractive for future mm-wave wearable WPT systems.
