Antenna designs for communication between a wirelessly powered implant to an external device outside the body
Methods and apparatus for wireless power transfer and communications are provided. In one embodiment, a wireless power transfer system comprises an external transmit resonator configured to transmit wireless power, an implantable receive resonator configured to receive the transmitted wireless power from the transmit resonator, and communications antenna in the implantable receive resonator configured to send communication information to the transmit resonator. The communications antenna can include a plurality of gaps positioned between adjacent conductive elements, the gaps being configured to prevent or reduce induction of current in the plurality of conductive elements when the antenna is exposed to a magnetic field.
1. An antenna for use in a wireless power system, comprising:
a differential transmission line;
a plurality of conductive elements coupled to the differential transmission line and configured to radiate RF energy to transmit and receive radio information, wherein a first conductive element of the plurality of conductive elements and a second conductive element of the plurality of conductive elements are physically coupled to the differential transmission line, wherein remaining conductive elements of the plurality of conductive elements are not physically coupled to the differential transmission line, wherein a first subset of the plurality of conductive elements defines a first electrical path comprising an interior trace of the antenna, wherein a second subset of the plurality of conductive elements defines a second electrical path comprising an exterior trace of the antenna, wherein the first subset is different from the second subset, and wherein the first and second subsets both include the first conductive element and the second conductive element; and
a plurality of gaps positioned between adjacent conductive elements, the gaps configured to prevent or reduce induction of current in the plurality of conductive elements when the antenna is exposed to a magnetic field.
2. The antenna of claim 1 , wherein the first electrical path is tuned to a first resonant frequency, and the second electrical path is tuned to a second resonant frequency.
3. A wireless receiver for use in a TET system, comprising:
a hermetically sealed housing;
receiver electronics contained in the hermetically sealed housing;
a low-frequency ferrite material surrounding the hermetically sealed housing, the low-frequency ferrite material configured to reduce the amount of magnetic flux that reaches the hermetically sealed housing;
an antenna body coupled to the low-frequency ferrite material;
a plurality of conductive elements disposed on the antenna body;
a differential transmission line electrically connecting the plurality of conductive elements to the receiver electronics and configured to deliver RF energy to the plurality of conductive elements to transmit and receive radio information; and
a plurality of gaps positioned between adjacent conductive elements, the gaps configured to prevent or reduce induction of current in the plurality of conductive elements when the antenna is exposed to a magnetic field.
4. The wireless receiver of claim 3 , wherein the plurality of conductive elements define a first electrical path and a second electrical path.
5. The wireless receiver of claim 4 , wherein the first electrical path comprises an interior trace of the antenna, and the second electrical path comprises an exterior trace of the antenna.
6. The wireless receiver of claim 5 , wherein the first electrical path is tuned to a first resonant frequency, and the second electrical path is tuned to a second resonant frequency.
7. The wireless receiver of claim 3 , further comprising a high-frequency ferrite material positioned between the plurality of conductive elements and the low-frequency ferrite material.
8. A communications antenna, comprising:
a differential transmission line;
a plurality of conductive elements coupled to the differential transmission line and configured to radiate RF energy to transmit and receive radio information, wherein a first conductive element of the plurality of conductive elements and a second conductive element of the plurality of conductive elements are physically coupled to the differential transmission line, wherein remaining conductive elements of the plurality of conductive elements are not physically coupled to the differential transmission line, wherein a first subset of the plurality of conductive elements defines a first electrical path comprising an interior trace of the antenna, wherein a second subset of the plurality of conductive elements defines a second electrical path comprising an exterior trace of the antenna, wherein the first subset is different from the second subset, and wherein the first and second subsets both include the first conductive element and the second conductive element; and
a plurality of gaps positioned between adjacent conductive elements, the gaps configured to prevent or reduce induction of current in the plurality of conductive elements when the antenna is exposed to a magnetic field.