On the Design of Efficient Multi-Coil Telemetry System for Biomedical Implants

Abstract

Two-coil based inductive coupling is a commonly used technique for wireless power and data transfer for biomedical implants. Because the source and load resistances are finite, two-coil systems generally achieve a relatively low power transfer efficiency. A novel multi-coil technique (using more than two coils) for wireless power and data transfer is considered to help overcoming this limitation. The proposed multi-coil system is formulated using both network theory and a two-port model. Using three or four coils for the wireless link allows for the source and load resistances to be decoupled from the Q-factor of the coils, resulting in a higher Q -factor and a corresponding improved power transfer efficiency (PTE). Moreover, due to the strong coupling between the driver and the transmitter coil (and/or between the receiver and the load coil), the multi-coil system achieves higher tunable frequency bandwidth as compared to its same sized two-coil equivalent. Because of the wider range of reflected impedance in the multi-coil system case, it is easier to tune the output power to the load and achieve the maximum power transfer condition for given source voltage than in a configuration with two coils. Experimental results showing a three-coil system achieving twice the efficiency and higher gain-bandwidth product compared to its two-coil counterpart are presented. In addition, a figure of merit for telemetry systems is defined to quantify the overall telemetry system performance.

Design Optimization Method for the Load Impedance to Maximize the Output Power in Dual Transmitting Resonator Wireless Power Transfer System

“…Resistance R o represents the load impedance. Furthermore, i 1 , i 2 and i 3 are the current flowing in the transmitting and receiving resonators, respectively; v 13 and v 23 are the voltage induced by the mutual inductance between coils W1 and W3 and between coils W2 and W3, respectively.…”

Optimization of a Dual-Band Wireless Power and Data Telemetry System Using Genetic Algorithm

“…The proposed topology is much easier to manufacture compared with the orthogonal approach in [26] and takes less area compared with the non-overlapping approach in [27]. Through the proposed optimization procedure, it also achieves good performance without an additional transmitting coil used in [28].…”

Analysis and Optimization of Three-Resonator Wireless Power Transfer System for Predetermined-Goals Wireless Power Transmission

“…To extend the transmission distance of traditional two-resonator MCWPT system further, a method of inserting intermediate resonators (IX) between the transmitter (TX) and the receiver (RX) to form three-resonator system has been proposed recently [7][8][9][10][11][12][13][14][15][16]. It has proved in [7] that three-resonator WPT system with IX close to TX or RX can achieve a relatively high power transfer efficiency (PTE) at original resonate frequency compared two-resonator counterpart. Ahn and Hong [8] pointed out that power transmission can be maximized at original resonant frequency via inserting a resonator in traditional two-resonator system.…”