A Low-Operating-Voltage Wireless Intermediate-Range Scheme for Energy and Signal Transmission by Magnetic Coupling for Implantable Devices

The increasing sophistication and power demands of medical implantable devices have motivated a variety of research on wireless energy transmission, aiming to provide higher power capability, wider receiver position, and improved performance, including safety and efficiency. This paper demonstrates a low-operating-voltage wireless energy and signal transmission method to achieve these aims. We developed a 30-cm transmitting coil in a Helmholtz-coil configuration. Innovative coil segmentation and distributive resonance techniques are employed to substantially reduce the excitation voltage and the voltage over the coil. Magnetic field simulations show that the magnetic field generated by the scheme is uniform and applicable in a wide region bounded by the coils. The receiving coil has three turns and a diameter of 2 cm. The receiver can deliver 350 mW when the transmitting coil excitation is 1 Arms/6.68 Vrms and the maximum voltage over the coil is 32 Vrms, which is much lower than that required in the most up-to-date method (5 A/3.5 kV). This method can provide sufficient power to operate many kinds of medical implants, especially deep-seated and locomotive devices, such as capsule endoscopes. An operating frequency of 6.1 MHz is chosen. At such a high frequency, the receiving coil does not need ferromagnetic core so magnetic resonance imaging compatible implants can be accomplished.