Wireless midfield systems and methods
Implantable devices and/or sensors can be wirelessly powered by controlling and propagating electromagnetic waves in a patient's tissue. Such implantable devices/sensors can be implanted at target locations in a patient, to stimulate areas such as the heart, brain, spinal cord, or muscle tissue, and/or to sense biological, physiological, chemical attributes of the blood, tissue, and other patient parameters. The propagating electromagnetic waves can be generated with sub-wavelength structures configured to manipulate evanescent fields outside of tissue to generate the propagating waves inside the tissue. Methods of use are also described.
1. A system for wirelessly transmitting power and/or data from a body-external source device to one or more implanted devices, the system comprising:
a substantially planar substrate including slot voids in the substrate, the slot voids including at least two elongated and intersecting slots, wherein the substrate is configured to be provided substantially parallel with a tissue surface for transferring wireless signals to the one or more implanted devices; and
multiple excitation ports coupled to the substrate adjacent or near to the slot voids in the substrate, wherein the excitation ports are configured to receive respective drive signals from a controller.
2. The system of claim 1 , wherein when the multiple excitation ports receive the respective drive signals from the controller, the system is configured to manipulate an evanescent field near the tissue surface to thereby generate a non-stationary field inside the tissue.
3. The system of claim 1 , wherein when the multiple excitation ports receive the respective drive signals from the controller and the substrate is positioned parallel with the tissue surface, the system is configured to generate a propagating field inside the tissue.
4. The system of claim 1 , wherein the multiple excitation ports are provided at substantially equal intervals at opposite sides of the substrate.
5. The system of claim 1 , wherein the slot voids in the substrate include multiple elongated voids arranged to form a portion of an “X” pattern and the slot voids further include an annular slot void.
6. The system of claim 5 , wherein the multiple excitation ports are provided at or near intersections of the annular slot void and one or more of the elongated voids.
7. The system of claim 6 , wherein the elongated voids comprise two linear void areas that are arranged substantially perpendicular to one another.
8. The system of claim 1 , wherein the slot voids in the substrate include multiple linear void areas that extend radially away from a center of the substrate.
9. The system of claim 1 , wherein the substrate includes multiple different instances of slot void pairs wherein each of the pairs includes elongated voids that intersect.
10. The system of claim 9 , wherein the excitation ports are respectively coupled to the different instances.
11. The system of claim 1 , further comprising the controller, wherein the controller is configured to provide the respective drive signals in a range from about 300 MHz to 3 GHz.
12. The system of claim 11 , wherein the controller is configured to provide the respective drive signals with respective different amplitude and/or phase characteristics.
13. The system of claim 1 , wherein substantially circular current paths are generated about a surface of the substrate when the excitation ports are excited by the drive signals from the controller.
14. A system for wirelessly transmitting power and/or data from an external transmitter to one or multiple implanted devices, the system comprising:
a substantially planar substrate with multiple slots therein, the slots including at least two elongated voids that intersect, wherein the substrate is configured to be provided substantially parallel with a tissue surface when in use to transfer wireless signals to the one or more implanted devices;
multiple excitation ports provided at respective locations about the substrate; and
an excitation signal generator circuit configured to provide respective drive signals to the excitation ports.
15. The system of claim 14 , wherein when the multiple excitation ports receive the respective drive signals from the excitation signal generator circuit, the external transmitter is configured to manipulate an evanescent field near the tissue surface to provide a non-stationary field inside the tissue.
16. The system of claim 14 , wherein when the multiple excitation ports receive the respective drive signals from the excitation signal generator circuit and the substrate is positioned parallel with the tissue surface, the external transmitter is configured to generate a propagating field inside the tissue.
17. The system of claim 14 , wherein the slots in the substrate include an annular void that intersects with at least one of the elongated voids.
18. The system of claim 14 , wherein the excitation signal generator is configured to provide the respective drive signals in a range from about 300 MHz to 3 GHz, and wherein each of the respective drive signals has a different phase characteristic.
19. The system of claim 14 , wherein substantially circular current paths are generated about a surface of the substrate when the excitation ports are excited by the drive signals from the excitation signal generator circuit.
20. An external transmitter for wirelessly communicating power and/or data to a device implanted in body tissue, the external transmitter comprising:
a substantially planar substrate with multiple slots therein, the slots including at least two elongated voids that extend radially away from a central axis of the substrate without intersecting at the central axis, wherein the substrate is configured to be provided substantially parallel with a tissue surface to transfer wireless signals to the device implanted in body tissue;
multiple excitation ports provided at respective locations about the substrate; and
an excitation signal generator circuit configured to provide respective drive signals to the excitation ports;
wherein when the multiple excitation ports receive the respective drive signals from the excitation signal generator circuit, the external transmitter is configured to manipulate an evanescent field near the tissue surface to provide a non-stationary field inside the tissue.