Configurable photoplethysmogram system
Methods, systems, and devices for optical signal measurement are described. A wearable electronic device may activate a first combination of optical sensors, the first combination of optical sensors including a set of transmitter sensors and a set of receiver sensors. In some cases, one or more optical sensor of the first combination of optical sensors may be positioned under a protrusion on an inner surface of the wearable electronic device. The device may measure, at the set of receiver sensors at a first time, one or more signals from the set of transmitter sensors, determine a signal quality metric associated with the one or more signals, and select a second combination of optical sensors for use at a second time based on the signal quality metric.
1. A method for measuring optical signals by a wearable electronic device, comprising:
activating a first combination of optical sensors, the first combination of optical sensors comprising a set of transmitter sensors from a plurality of transmitter sensors and a set of receiver sensors from a plurality of receiver sensors of the wearable electronic device, wherein the plurality of transmitter sensors comprises at least one transmitter sensor of a first wavelength, at least one transmitter sensor of a second wavelength, and at least one transmitter sensor of a third wavelength, and wherein at least one optical sensor of the first combination of optical sensors is positioned under a protrusion on an inner surface of the wearable electronic device;
measuring, at the set of receiver sensors at a first time, one or more signals from the set of transmitter sensors;
determining a signal quality metric associated with the one or more signals; and
selecting a second combination of optical sensors for use at a second time based at least in part on the signal quality metric.
2. The method of claim 1 , wherein selecting the second combination of optical sensors comprises:
selecting a second set of transmitter sensors, a second set of receiver sensors, or a combination thereof, based at least in part on the signal quality metric.
3. The method of claim 2 , wherein the second set of transmitter sensors and the second set of receiver sensors are positioned around the wearable electronic device, and wherein selecting the second combination of optical sensors is based at least in part on a positioning of the second set of transmitter sensors and the second set of receiver sensors.
4. The method of claim 1 , wherein the wearable electronic device comprises a first photodiode and a second photodiode, the first photodiode and the second photodiode located under a first protrusion and a second protrusion, respectively, in the wearable electronic device.
5. The method of claim 4 , wherein the at least one transmitter sensor of the first wavelength comprises a first green LED and a second green LED, the first green LED positioned to the right of the first photodiode and the second green LED positioned to the left of the second photodiode.
6. The method of claim 5 , wherein the at least one transmitter sensor of the second wavelength comprises an infrared LED, the infrared LED positioned to the right of the first green LED.
7. The method of claim 6 , wherein the at least one transmitter sensor of the third wavelength comprises a red LED, the red LED positioned to the left of the second green LED, the red LED and the infrared LED positioned next to one another.
8. The method of claim 7 , wherein the infrared LED and the red LED are positioned under a third protrusion in the wearable electronic device.
9. The method of claim 1 , wherein selecting the second combination of optical sensors comprises:
selecting a pair of optical sensors, the pair of optical sensors comprising at least one transmitter optical sensor and at least one receiver optical sensor.
10. The method of claim 1 , wherein measuring the one or more signals comprises:
measuring, by the set of receiver sensors, a photoplethysmogram (PPG) signal from the set of transmitter sensors.
11. The method of claim 10 , wherein determining the signal quality metric further comprises:
determining an amplitude of the PPG signal, an amount of noise in the PPG signal, a form of the PPG signal, a power consumption associated with determining the PPG signal, or a combination thereof.
12. The method of claim 1 , further comprising:
selecting a wavelength from a set of wavelengths based at least in part on a set of parameters for use in generating the one or more signals, wherein selecting the second combination of optical sensors is based at least in part on the selected wavelength.
13. The method of claim 12 , wherein selecting the second combination of optical sensors comprises:
selecting between the at least one transmitter sensor of the first wavelength or the at least one transmitter sensor of the second wavelength.
14. The method of claim 1 , wherein determining the signal quality metric comprises:
determining a signal quality, a time of day, a motion of a user of the wearable electronic device, a temperature, a wavelength associated with the first set of optical sensors, or a combination thereof.
15. The method of claim 1 , further comprising:
updating one or more of a sampling rate, a power output level, or a sensor activation time, associated with the first combination of optical sensors, the second combination of optical sensors, or both, based at least in part on the signal quality metric.
16. The method of claim 1 , further comprising:
detecting an ambient light with one or more receiver sensors of the plurality of receiver sensors;
determining that the detected ambient light exceeds a threshold; and
identifying a ring fit metric based at least in part on determining that the detected ambient light exceeds the threshold, wherein the ring fit metric indicates a gap between the inner surface of the wearable electronic device and skin of a user wearing the wearable electronic device.
17. The method of claim 1 , wherein at least one transmitter sensor of the second wavelength comprises an infrared LED that is dedicated for finger wearing detection, the method further comprising:
activating the infrared LED that is dedicated for the finger wearing detection; and
determining whether the wearable electronic device is being worn by a user based at least in part on whether the activated infrared LED that is dedicated for the finger wearing detection is detected by one or more of the plurality of receiver sensors.
18. A wearable electronic device, comprising:
a set of receiver sensors positioned on an inner surface of the wearable electronic device, the inner surface contacting a user of the wearable electronic device when the user is wearing the wearable electronic device, at least one receiver sensor of the set of receiver sensors positioned under a protrusion on the inner surface of the wearable electronic device;
a first set of transmitter sensors positioned adjacent the set of receiver sensors on the inner surface, wherein the first set of transmitter sensors comprises one or more transmitter sensors of a first wavelength; and
a second set of transmitter sensors positioned adjacent the set of receiver sensors on the inner surface, wherein the second set of transmitter sensors comprises at least one transmitter sensor of a second wavelength and at least one transmitter sensor of a third wavelength.
19. The wearable electronic device of claim 18 , wherein the set of receiver sensors comprises at least two photodiodes, the first set of transmitter sensors comprises at least two green LEDs, and the second set of transmitter sensors comprises at least one infrared LED and at least one red LED.
20. An apparatus for measuring optical signals by a wearable electronic device, comprising:
a processor;
memory coupled with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
activate a first combination of optical sensors, the first combination of optical sensors comprising a set of transmitter sensors from a plurality of transmitter sensors and a set of receiver sensors from a plurality of receiver sensors of the wearable electronic device, wherein the plurality of transmitter sensors comprises at least one transmitter sensor of a first wavelength, at least one transmitter sensor of a second wavelength, and at least one transmitter sensor of a third wavelength, and wherein at least one optical sensor of the first combination of optical sensors is positioned under a protrusion on an inner surface of the wearable electronic device;
measure, at the set of receiver sensors at a first time, one or more signals from the set of transmitter sensors;
determine a signal quality metric associated with the one or more signals; and
select a second combination of optical sensors for use at a second time based at least in part on the signal quality metric.