Methods, systems, and devices for determining a respiration rate

1. A wearable device comprising:

a sensor configured to capture photoplethysmographic (PPG) signals;

a processor;

a communication interface, wherein the communication interface is configured to connect the wearable device to a remote computing device; and

a controller, configured to:

(i) receive from the sensor over a non-zero time period a PPG signal;

(ii) make a first determination that, during the non-zero time period, the wearable device has moved less than a threshold amount;

(iii) in response to the first determination that, during the non-zero time period, the wearable device has moved less than the threshold amount, determine from the PPG signal at least one variation signal indicative of a variation induced by respiration and determine in each of a plurality of frequency bins a power level of the at least one variation signal;

(iv) send to the remote computing device via the communication interface data related to the at least one variation signal; and

(v) receive from the remote computing device via the communication interface a signal that includes data indicative of whether a respiration rate is determinable.

2. The wearable device of claim 1 , wherein the data related to the at least one variation signal comprises data indicative of each determined power level.

3. The wearable device of claim 1 , wherein the at least one variation signal includes a respiratory-induced intensity variation (RIIV) signal.

4. The wearable device of claim 1 , wherein the at least one variation signal includes a respiratory-induced amplitude variation (RIAV) signal.

5. The wearable device of claim 1 , wherein the at least one variation signal includes a respiratory-induced frequency variation (RIFV) signal.

6. The wearable device of claim 1 , wherein the at least one variation signal includes at least a first variation signal and a second variation signal.

7. The wearable device of claim 6 , wherein the controller is further configured to:

if the signal from the remote computing device indicates that a respiration rate is determinable, determine the respiration rate based on at least the first variation signal and the second variation signal.

8. The wearable device of claim 7 , wherein the controller is configured to determine the respiration rate by a process comprising:

determining a first preliminary respiration rate based on the first variation signal;

determining a second preliminary respiration rate based on the second variation signal; and

combining the first and second preliminary respiration rates.

9. The wearable device of claim 8 , wherein determining the first preliminary respiration rate comprises identifying a first peak in the first variation signal, wherein determining the second preliminary respiration rate comprises identifying a second peak in the second variation signal, wherein the first peak and the second peak each have a frequency within a range of respiration frequencies.

10. The wearable device of claim 7 , further comprising an output component, wherein the controller is further configured to provide a notification via the output component based on the determined respiration rate.

11. The wearable device of claim 10 , wherein the notification includes at least one of a visual output or an auditory output.

12. The wearable device of claim 1 , wherein the sensor comprises a light emitter and a light detector.

13. The wearable device of claim 1 , further comprising a second sensor configured to capture movement data of the wearable device, wherein the controller is further configured to receive, from the second sensor and over the non-zero time period, movement data of the wearable device.

14. The wearable device of claim 13 , wherein the second sensor comprises one or more accelerometers, gyrometers, and/or magnetometers.

15. The wearable device of claim 1 , further comprising:

a mount, wherein the mount secures the device to an external body surface.

16. The wearable device of claim 15 , wherein the external body surface is a location on a wrist.

17. The wearable device of claim 15 , wherein the mount comprises at least one of a band or an adhesive substrate.

18. The wearable device of claim 7 , further comprising:

a user interface, wherein the controller is further configured to cause the user interface to indicate information relating to the determined respiration rate.

19. The wearable device of claim 18 , wherein the user interface comprises a display.