Adaptive transmitting coil array for optimal power transfer in deeply implanted medical devices

In the design of implantable devices, providing the wireless power to the device presents one of the critical parts of the system design and RF power harvesting through inductive coupling presents a commonly used solution. The maximum power transfer in the inductive link occurs when the transmitting and receiving circular coils are aligned on the same central axes. However, when there is either angular or lateral misalignment between the coils, the maximum delivered power to the receiving coil can be significantly reduced. We propose a design of an array of coils instead of a single transmitting coil that through adaptive control of the phase of the coil feed currents optimizes the power transfer when misalignment exists. We demonstrate that the two coil transmitting antenna provides increase in the power efficiency compared to the same area single coil when both angular and lateral misalignment exist in a smart pill application.