Antenna and methods of use for an implantable nerve stimulator
A pulse generator that includes a communications module is disclosed herein. The communication module includes a transceiver and an antenna circuit. The antenna circuit includes a first pathway having a capacitor and a second, parallel pathway including a capacitor, and a resistor, and a radiating element arranged in series. The antenna circuit is tuned to have a resonant frequency corresponding to a desired transmission frequency and a bandwidth corresponding to shifts in the resonant frequency arising from the implantation of the antenna.
1. An implantable neurostimulator for delivering one or more electrical pulses to a target region within a patient's body according to a program received via wireless communication with an external device, the implantable neurostimulator comprising:
a hermetic housing having an external surface comprising a biocompatible material that is configured to be implanted within a body of a patient;
a transceiver disposed within the hermetic housing and comprising a first lead and a second lead; and
a communication antenna circuit disposed within the hermetic housing and coupled to the first lead and the second lead, the communication antenna circuit comprising a printed circuit board (PCB) having a first path and a second path parallel to the first path, the first path comprising a first capacitor, and the second path comprising:
a second capacitor;
a radiating element comprising a plurality of conductive loops; and
a resistor, wherein the second capacitor, the resistor, and the radiating element are arranged in series.
2. The implantable neurostimulator of claim 1 , wherein the plurality of conductive loops are located along a common plane of the PCB.
3. The implantable neurostimulator of claim 2 , wherein the radiating element crosses another portion of the second path.
4. The implantable neurostimulator of claim 3 , wherein the common plane of the radiating element is located at a different depth in the PCB than the other portion of the second path crossed by the radiating element.
5. The implantable neurostimulator of claim 3 , wherein the radiating element comprises a necked down portion, wherein the radiating element crosses the other portion of the second path via the necked down portion.
6. The implantable neurostimulator of claim 3 , wherein the conductive loops comprise copper traces embedded onto a substrate surface of the PCB, and wherein the copper traces are configured to produce an electric field dipole having a donut pattern with a maximum strength in the common plane such that a maximum field is substantially normal to a body surface of the patient when the hermetic housing is implanted for use.
7. The implantable neurostimulator of claim 6 , wherein the plurality of conductive loops comprises a first loop and a second loop, wherein the second loop is located within the first loop.
8. The implantable neurostimulator of claim 7 , wherein the communication antenna circuit has a fixed natural resonant frequency, the first capacitor has a first fixed capacitance and the second capacitor has a second fixed capacitance.
9. The implantable neurostimulator of claim 8 , wherein the communication antenna circuit is defined by a Q factor and the resistor is configured to diminish the Q factor of the communication antenna circuit such that a bandwidth of the communication antenna circuits encompasses patient implantation-related variability in resonant frequency when the communication antenna circuit is implanted in the patient body and communicates with the external device.
10. The implantable neurostimulator of claim 8 , wherein the fixed resonant frequency corresponds to a transmitting frequency at which the implantable neurostimulator is configured to receive one or more wireless communications, and wherein the communication antenna circuit has a bandwidth such that an effectiveness of the communication antenna circuit at receiving the transmitting frequency does not drop below a half-power point of the communication antenna circuit when implanted within the body of the patient.
11. The implantable neurostimulator of claim 1 , further comprising a charging coil assembly comprising: a core; and a charging coil wound around the core.
12. The implantable neurostimulator of claim 11 , wherein the communication antenna circuit is positioned between the charging coil assembly and an end of the hermetic housing.
13. The implantable neurostimulator of claim 12 , further comprising at least one bumper extending from the communication antenna circuit and towards the end of the hermetic housing.
14. A method of wireless communication between an implantable neurostimulator and an external device, the method comprising:
receiving data at a transmission frequency with a communication antenna circuit of the implantable neurostimulator from the external device, the communication antenna circuit having a first resonant frequency corresponding to the transmission frequency when the implantable neurostimulator is ex vivo and a second resonant frequency when the implantable neurostimulator is in vivo, the communication antenna circuit disposed within a hermetic housing of the implantable neurostimulator and comprising a printed circuit board (PCB) having a first path and a second path parallel to the first path, the first path comprising a capacitor, and the second path comprising: a second capacitor; a radiating element comprising a plurality of conductive loops; and a resistor, wherein the second capacitor, the resistor, and the radiating element are arranged in series, and wherein the communication antenna circuit has a bandwidth such that an output power of the communication antenna circuit at both the first and second resonant frequencies is greater than the half-power point of the communication antenna circuit;
controlling the implantable neurostimulator according to the received data; and
transmitting data at the second resonant frequency via the communication antenna circuit.
15. The method of claim 14 , further comprising delivering at least electrical pulse to a target tissue via at least one stimulation lead according to the control of the implantable neurostimulator.
16. The method of claim 15 , further comprising delivering a first electrical pulse to the target tissue via the at least one stimulation lead before receiving the data.
17. The method of claim 16 , wherein the radiating element comprises a plurality of conductive loops located along a common plane of the PCB.
18. The method of claim 17 , wherein the radiating element crosses another portion of the second path.
19. The method of claim 18 , wherein the common plane of the radiating element is located at a different depth in the PCB than the other portion of the second path crossed by the radiating element.
20. The method of claim 18 , wherein the radiating element comprises a necked down portion, wherein the radiating element crosses the other portion of the second path via the necked down portion.
21. The method of claim 17 , wherein, during transmitting data, the communication antenna circuit is configured to generate an electric field dipole having a donut pattern with a maximum strength in the common plane such that a maximum field is substantially normal to a body surface of a patient when the hermetic housing is implanted for use.
22. The method of claim 14 , further comprising: receiving energy with a charging coil assembly of the implantable neurostimulator; and recharging a battery of the implantable neurostimulator with the received energy.
23. The method of claim 22 , wherein the charging coil assembly comprises: a core; and a charging coil wound around the core.
24. The method of claim 23 , wherein the communication antenna circuit is positioned between the charging coil assembly and an end of the hermetic housing.