Orthogonally oriented coils for minimization of cross-coupling in cortical implants

This article presents the design of the inductive links of remotely powered wireless cortical implants for minimum interference from the power link to the data link. This interference is minimized by changing the orientation of the inductors. Different orientation types are investigated and compared. Orthogonally oriented coils with high interference suppression and better reproducibility has been proposed. From the simulations, 29% power efficiency and 46 dB interference suppression is achieved for these coils. The spiral inductors are fabricated on PCBs and results of preliminary measurements are presented. Moreover, a conceptual cortical implant prototype is proposed. © 2008 IEEE

Improvement of power efficiency of inductive links for implantable devices

This paper presents the analysis of inductive links for remote powering of implantable devices and a method to improve the power link efficiency by modifying the geometrical parameters of planar spiral inductors. The analysis of the inductive links includes a model for the inductors, which is more accurate for larger bandwidths. The corresponding equations for the power and voltage transfer functions in the inductive links are solved by using MATLAB's Symbolic Math Toolbox. These equations are verified in Agilent ADS, and the results perfectly match. Besides the analysis, a method to improve the power efficiency by changing the geometrical parameters of the spiral inductors is proposed. © 2008 IEEE

Load optimization of an inductive power link for remote powering of biomedical implants

This article presents the analysis of the power efficiency of the inductive links used for remote powering of the biomedical implants by considering the effect of the load resistance on the efficiency. The optimum load condition for the inductive links is calculated from the analysis and the coils are optimized accordingly. A remote powering link topology with a matching network between the inductive link and the rectifier has been proposed to operate the inductive link near its optimum load condition to improve overall efficiency. Simulation and measurement results are presented and compared for different configurations. It is shown that, the overall efficiency of the remote powering link can be increased from 9.84% to 20.85% for 6 mW and from 13.16% to 18.85% for 10 mW power delivered to the regulator, respectively