Enhanced wireless communication and power transfer between external and implanted devices
Systems, devices, and methods are discussed herein for wirelessly transmitting power and/or data to an implanted device, such as an implanted electrostimulator device. In an example, the subject matter includes a layered transmitter device with multiple conductive planes and excitation features. The transmitter device can be tuned to identify and apply device parameters for efficient wireless communication with a deeply implanted device. The transmitter is generally configured for midfield powering applications by providing signals that give rise to propagating signals inside of body tissue.
1. A method for enhancing wireless communication from an external midfield transmitter device to an implanted receiver device, wherein the midfield transmitter device includes at least two conductive regions and a stripline, the method comprising:
providing an excitation signal to the stripline and, concurrently or in response, monitoring a signal transmission coupling characteristic between the midfield transmitter device and the implanted receiver device; and
adjusting an electrical coupling characteristic between the conductive regions of the midfield transmitter device based on the signal transmission coupling characteristic.
2. The method of claim 1 , wherein monitoring the signal transmission coupling characteristic includes using a relationship between the excitation signal and a reflected signal.
3. The method of claim 1 , wherein monitoring the signal transmission coupling characteristic includes monitoring information about a reflected power signal to the midfield transmitter device.
4. The method of claim 1 , wherein monitoring the signal transmission coupling characteristic includes monitoring information about a reflected portion of a signal transmitted by the external midfield transmitter device in response to the excitation signal.
5. The method of claim 1 , wherein monitoring the signal transmission coupling characteristic includes monitoring information about a voltage standing wave ratio (VSWR).
6. The method of claim 1 , wherein providing the excitation signal to the stripline includes using the external midfield transmitter device to communicate a first signal to the implanted receiver device; and
wherein monitoring the signal transmission coupling characteristic includes receiving information from the implanted receiver device about a quality of the first signal received by the implanted receiver device.
7. The method of claim 6 , wherein receiving information about the quality of the first signal includes receiving information about a magnitude of the first signal received by the implanted receiver device.
8. The method of claim 7 , wherein receiving information about the quality of the first signal includes receiving a backscatter signal at the external midfield transmitter device in response to the first signal communicated to the implanted receiver device.
9. The method of claim 1 , wherein adjusting the electrical coupling characteristic between the conductive regions of the midfield transmitter device comprises changing a capacitance of a capacitor that couples the conductive regions.
10. The method of claim 9 , wherein changing the capacitance of the capacitor comprises cycling through multiple different capacitance values for the capacitor and monitoring the signal transmission coupling characteristic at each of the multiple different capacitance values.
11. The method of claim 10 , further comprising determining a preferred capacitance value for the capacitor corresponding to a minimum amount of power reflected from the implanted receiver device.
12. The method of claim 1 , wherein adjusting the electrical coupling characteristic between the conductive regions of the midfield transmitter device based on the signal transmission coupling characteristic comprises changing a resonant frequency of the midfield transmitter device.
13. An external midfield transmitter device configured to wirelessly communicate with an implanted receiver device, the external midfield transmitter device comprising:
a processor circuit;
an emitter comprising first and second conductive regions spaced apart from an electrically excitable stripline;
a signal generator configured to provide a drive signal to the stripline; and
a capacitor coupling the first and second conductive regions, wherein a capacitance of the capacitor is configured to change in response to a control signal from the processor circuit;
wherein the processor circuit is configured to provide the control signal to change the capacitance of the capacitor based on a signal transmission coupling characteristic between the external midfield transmitter device and the implanted receiver device.
14. The external midfield transmitter of claim 13 , further comprising a bidirectional coupler provided in a signal path between the signal generator and the stripline,
wherein the processor circuit is configured to provide the control signal to change the capacitance of the capacitor based on information about a reflected power signal received from a port of the bidirectional coupler.
15. The external midfield transmitter of claim 14 , wherein the processor circuit is configured to provide the control signal to increase a capacitance of the capacitor when the information about the reflected power signal indicates a relatively greater amount of reflected power.
16. The external midfield transmitter of claim 13 , wherein the processor circuit is configured to determine the signal transmission coupling characteristic based on information about a reflected power signal to the midfield transmitter device.
17. An external midfield transmitter device configured to wirelessly communicate with an implanted receiver device, the external midfield transmitter device comprising:
a processor circuit;
an emitter comprising a reference node, a first conductive region spaced apart from the reference node, and a second conductive region spaced apart from the reference node;
a signal generator configured to provide respective drive signals to excitation structures that are proximal to the first and second conductive regions;
a first adjustable capacitor coupling the reference node and the first conductive region; and
a second adjustable capacitor coupling the reference node and the second conductive region;
wherein the processor circuit is configured to change capacitance characteristics of the first and second adjustable capacitors based on a signal transmission efficiency characteristic between the external midfield transmitter device and an implanted receiver device.
18. The external midfield transmitter device of claim 17 , wherein the processor circuit is configured to determine the signal transmission efficiency characteristic based on information about a reflected portion of a signal transmitted by the external midfield transmitter device to the implanted receiver device.
19. The external midfield transmitter device of claim 17 , further comprising the excitation structures, wherein the first and second conductive regions are coplanar, and wherein the excitation structures are spaced apart from the first and second conductive regions by a dielectric layer.
20. The external midfield transmitter device of claim 19 , further comprising first and second bidirectional couplers coupled to the signal generator and to respective ones of the excitation structures proximal to the first and second conductive regions, wherein the processor circuit is configured to receive reflected power signal information via each of the bidirectional couplers and, in response, change a capacitance value of at least one of the capacitors.