Abstract: A set of shielded coils for wireless power transmission into a medical implant is described in which the external, power transmission coil is blocked at least on one side by a shield with a broken ring and radial fingers while the power receiver coil inside the medical implant is surrounded by a shield having a broken ring connecting radial fingers and ribs around its circumference. The finger and rib configurations minimizes eddy currents in the shields. A ground plane of the implant's internal circuitry, which is within the shield along with the receiver coil, can cap off the cupped receiver shield to form a Faraday cage with it. The metal or other conductive shielding prevents large electric fields from the coils from penetrating into the tissue of the subject while simultaneously allowing magnetic fields inductively couple the coils for charging.

Abstract: A coil formed from a flexible polymer substrate that is printed with metal traces is disclosed in which the flexible substrate has notches that align each loop as the substrate is wound into a ring. The notches are precisely spaced so that the diameter of each loop is well controlled. As the substrate is wound, adhesive is applied along its length to fill gaps between each loop's layer. Ideally, the adhesive has a similar dielectric constant as the polymer substrate. The resulting coil has loops of metal traces separated by precise a thickness of dielectric. The precision in spacing between metal layers and dielectric allows the coil to be designed for self-resonance.