Systems and methods to locate an implantable stimulator device inside a subject
Implementations provide a method that includes: placing a controller device over a surface region of the patient where the implantable wireless stimulation device has been implanted; configuring the controller device to (i) monitor a return loss representing electrical power reflected from the implantable wireless stimulation device to the controller device; (ii) compute a first path loss metric based on a first monitored return loss when the controller device is place over a first location within the surface region; (iii) compute a second path loss metric based on a second monitored return loss when the controller device is over a second location within the surface region; and (iv) generate a feedback to an operator to indicate whether the second path loss is smaller than the first path loss such that the controller device is placed at a location with more electrical energy non-inductively transferred to the implantable wireless stimulation device.
1. A method to locate an implantable wireless stimulation device implanted inside a patient and configured to receive electrical energy wirelessly from outside the patient via non-inductive coupling, the method comprising:
placing a controller device over a surface region of the patient where the implantable wireless stimulation device has been implanted;
configuring the controller device to non-inductively couple to the implantable wireless stimulation device such that the implantable wireless stimulation device is wirelessly powered by electrical energy received non-inductively from the controller device, wherein the controller device is configured to:
monitor, by modulating an impedance of a receiving non-inductive antenna of the implantable wireless stimulation device, a return loss representing electrical power reflected from the implantable wireless stimulation device to the controller device when the implantable wireless stimulation device and the controller device are non-inductively coupled;
compute a first path loss metric that corresponds to a first instance of monitored return loss when the controller device is placed over a first location within the surface region;
compute a second path loss metric that corresponds to a second instance of monitored return loss when the controller device is placed over a second location within the surface region; and
generate a feedback to an operator to indicate whether the second path loss metric is smaller than the first path loss metric such that the controller device is placed at a location with more electrical energy non-inductively transferred to the implantable wireless stimulation device.
2. The method of claim 1 , further comprising:
configuring the controller device to obtain multiple instances of monitored return loss and perform a weighted sum of the multiple instances of the monitored return loss.
3. The method of claim 2 , further comprising:
configuring the controller device to obtain multiple instances of monitored return loss and implement a finite impulse response (FIR) filter to reduce noise contributions from the multiple instances of the monitored return loss.
4. The method of claim 3 , further comprising:
configuring the controller device to obtain multiple instances of monitored return loss and remove a baseline from the weighted sum of the multiple instances of the monitored return loss.
5. The method of claim 4 , wherein the baseline is removed by taking a time derivative of the multiple instances of the monitored return loss.
6. The method of claim 1 , further comprising:
configuring the controller device to generate a feedback by producing an audio signal to the operator indicating when more or less electrical energy is non-inductively transferred.
7. The method of claim 6 , wherein the audio signal is generated with increased pitch or amplitude when more electrical energy is non-inductively transferred at the second location than at the first location.
8. The method of claim 6 wherein the audio signal is generated with decreased pitch or amplitude when less electrical energy is non-inductively transferred at the second location than at the first location.
9. The method of claim 1 , further comprising:
configuring the controller device to generate a feedback by producing a visual signal to the operator indicating when more or less electrical energy is non-inductively transferred.
10. The method of claim 9 , wherein the visual signal is generated with increased blinking frequency or amplitude when more electrical energy is non-inductively transferred at the second location than at the first location.
11. The method of claim 9 , wherein the visual signal is generated with decreased blinking frequency or amplitude when less electrical energy is non-inductively transferred at the second location than at the first location.
12. The method of claim 1 , further comprising:
configuring the controller device to generate a haptic feedback to the operator indicating when more or less electrical energy is non-inductively transferred.
13. The method of claim 12 , wherein the haptic feedback is generated with increased vibration frequency or amplitude when more electrical energy is non-inductively transferred at the second location than at the first location.
14. The method of claim 12 , wherein the haptic feedback is generated with decreased blinking frequency when less electrical energy is non-inductively transferred at the second location than at the first location.
15. A system comprising:
a controller device comprising an antenna, a processor, and one or more memory storage devices;
an implantable wireless stimulation device comprising:
a non-inductive antenna configured to receive an input signal from the antenna of the controller device via radiative coupling;
a circuit configured to extract electric energy from the input signal such that implantable wireless stimulation device is wirelessly powered by the electrical energy extracted from the input signal; and
one or more electrodes configured to stimulate neural tissue of a subject using the electric energy extracted from the input signal,
wherein the controller device is configured to:
monitor, by modulating an impedance of the non-inductive antenna of the implantable wireless stimulation device, a return loss representing electrical power reflected from the implantable wireless stimulation device to the controller device when the implantable wireless stimulation device and the controller device are non-inductively coupled;
compute a first path loss metric that corresponds to a first instance of monitored return loss when the controller device is placed over a first location within a surface region of the subject;
compute a second path loss metric that corresponds to a second monitored return loss when the controller device is placed over a second location within the surface region of the subject; and
generate a feedback to indicate whether the second path loss metric is smaller than the first path loss metric such that the controller device is placed at a location with more electrical energy non-inductively transferred to the implantable wireless stimulation device.
16. The system of claim 15 , wherein the controller device is configured to obtain multiple instances of monitored return loss and perform a weighted sum of the multiple instances of the monitored return loss measurement.
17. The system of claim 16 , wherein the controller device is further configured to obtain multiple instances of monitored return loss and implement a finite impulse response (FIR) filter to reduce noise contributions from the multiple instances of the monitored return loss.
18. The system of claim 17 , wherein the controller device is further configured to obtain multiple instances of monitored return loss and remove a baseline from the weighted sum of the multiple instances of the monitored return loss.
19. The system of claim 15 , wherein the feedback comprises at least one of: an audio feedback, a visual feedback, or a haptic feedback.