User-worn device for noninvasively measuring a physiological parameter of a user
The present disclosure relates to noninvasive methods, devices, and systems for measuring various blood constituents or analytes, such as glucose. In an embodiment, a light source comprises LEDs and super-luminescent LEDs. The light source emits light at at least wavelengths of about 1610 nm, about 1640 nm, and about 1665 nm. In an embodiment, the detector comprises a plurality of photodetectors arranged in a special geometry comprising one of a substantially linear substantially equal spaced geometry, a substantially linear substantially non-equal spaced geometry, and a substantially grid geometry.
1. A user-worn device configurable to non-invasively measure oxygen saturation of a user, the user-worn device comprising:
a first set of light emitting diodes (LEDs), the first set of LEDs comprising at least an LED configured to emit visible light and an LED configured to emit near-infrared light;
a second set of LEDs spaced apart from the first set of LEDs, the second set of LEDs comprising at least an LED configured to emit visible light and an LED configured to emit near-infrared light;
at least two photodiodes spaced apart from one another and configured to receive light after attenuation by tissue of the user;
a protruding convex surface extending across the at least two photodiodes;
a first window in the protruding convex surface and aligned with a first photodiode of the at least two photodiodes;
a second window in the protruding convex surface and aligned with a second photodiode of the at least two photodiodes, wherein the first window and the second window are different windows; and
one or more processors configurable to receive one or more signals from at least one of the photodiodes and calculate a measurement of oxygen saturation of the user,
wherein at least the first photodiode is spaced a first distance from the first set of LEDs and a second distance from the second set of LEDs, and wherein the first and second distances are different.
2. The user-worn device of claim 1 , wherein, within each of the first and second sets of LEDs, any one LED is positioned within 2 mm to 4 mm of another.
3. The user-worn device of claim 1 , wherein the first distance creates a pathlength different from a pathlength created by the second distance.
4. The user-worn device of claim 3 , wherein the second photodiode is located a third distance from the first set of LEDs and a fourth distance from the second set of LEDs, and wherein the third and fourth distances are different.
5. The user-worn device of claim 4 , wherein the first photodiode is configured to receive light emitted by the first set of LEDs and generate a first signal indicative of the received light, and wherein the second photodiode is configured to receive light emitted by the first set of LEDs and generate a second signal indicative of the received light.
6. The user-worn device of claim 5 , wherein the one or more processors is configured to receive at least the first signal and the second signal and calculate the measurement of oxygen saturation of the user.
7. The user-worn device of claim 6 , wherein the one or more processors use the first and second signals to reduce noise.
8. The user-worn device of claim 7 , wherein the first window is laterally spaced from the second window.
9. The user-worn device of claim 8 further comprising:
an optical isolation disposed between the first photodiode and the second photodiode.
10. The user-worn device of claim 9 , wherein the first photodiode is partitioned into a plurality of light sensing regions.
11. The user-worn device of claim 1 , wherein at least some LEDs of the first and second sets of LEDs emit light at different wavelengths.
12. The user-worn device of claim 1 , wherein at least one of the LEDs of the first and second sets of LEDs emits green light, and wherein at least a different one of the LEDs of the first and second sets of LEDs emits infrared light.
13. The user-worn device of claim 1 further comprising:
a network interface configured to wirelessly communicate the measurement of oxygen saturation to at least one of: a mobile phone or a computer network;
a user interface comprising a touch-screen display, wherein the user interface is configured to display indicia responsive to the measurement of oxygen saturation of the user;
a storage device configured to at least temporarily store at least the measurement; and
a strap configured to position the user-worn device on the user.
14. The user-worn device of claim 1 , wherein the one or more processors are configured to receive one or more signals from at least one of the photodiodes and calculate a measurement of a physiological parameter, the physiological parameter comprising at least one of: methemoglobin, carboxyhemoglobin, or carbon monoxide.
15. The user-worn device of claim 1 , wherein the one or more processors are configured to receive one or more signals from at least one of the photodiodes and calculate a measurement of a physiological parameter, the physiological parameter comprising total hemoglobin.
16. A user-worn device configurable to non-invasively measure oxygen saturation of a user, the user-worn device comprising:
a sensor configurable to measure oxygen saturation of the user, the sensor comprising:
a first light emitting diode (LED) configured to emit light at a first wavelength;
a second LED spaced apart from the first LED and configured to emit light at a second wavelength different from the first wavelength;
a first photodiode located a first separation distance from the first LED and a second separation distance from the second LED, the first separation distance being different from the second separation distance, the first photodiode configured to:
receive light that has traveled along a first light path from the first LED after attenuation by tissue of the user; and
generate a first signal indicative of the received light;
a second photodiode located a third separation distance from the first LED and a fourth separation distance from the second LED, the third separation distance being different from the fourth separation distance, the second photodiode configured to:
receive light that has traveled along a second light path from the first LED after attenuation by tissue of the user; and
generate a second signal indicative of the received light;
a protruding convex surface extending across the first and second photodiodes, wherein the protruding convex surface comprises an opaque material configured to reduce light piping;
a first window in the protruding convex surface and aligned with the first photodiode; and
a second window in the protruding convex surface and aligned with the second photodiode, the second window laterally spaced from the first window; and
one or more processors coupled to the first and second photodiodes and configured to determine a measurement of a physiological parameter of the user from at least the first signal and the second signal.
17. The user-worn device of claim 16 , wherein a length of the first light path is different from a length of the second light path.
18. The user-worn device of claim 17 , wherein the one or more processors use the first and second signals to reduce noise.
19. The user-worn device of claim 18 further comprising:
an optical isolation disposed between the first photodiode and the second photodiode.
20. The user-worn device of claim 19 , wherein the first photodiode is partitioned into a plurality of light sensing regions, and wherein the second photodiode is partitioned into a plurality of light sensing regions.
21. The user-worn device of claim 16 further comprising:
a first set of LEDs including the first LED; and
a second set of LEDs including the second LED.
22. The user-worn device of claim 21 , wherein, within each of the first and second sets of LEDs, any one LED is positioned within 2 mm to 4 mm of another.
23. The user-worn device of claim 21 , wherein, within each of the first and second sets of LEDs, the LEDs emit light at different wavelengths.
24. The user-worn device of claim 23 , wherein the different wavelengths include at least green light and infrared light.
25. The user-worn device of claim 16 , wherein:
the first photodiode is further configured to:
receive light that has traveled along a third light path from the second LED after attenuation by tissue of the user; and
generate a third signal indicative of the received light;
the second photodiode is further configured to:
receive light that has traveled along a fourth light path from the second LED after attenuation by tissue of the user; and
generate a fourth signal indicative of the received light; and
the one or more processors are further configured to determine the measurement of the physiological parameter of the user from at least the first signal, the second signal, the third signal, and the fourth signal.
26. The user-worn device of claim 16 further comprising:
a network interface configured to wirelessly communicate the measurement of the physiological parameter to at least one of: a mobile phone or a computer network;
a user interface comprising a touch-screen display, wherein the user interface is configurable to display indicia responsive to the measurement of the physiological parameter and the measurement of oxygen saturation of the user;
a storage device configured to at least temporarily store at least the measurement; and
a strap configured to position the user-worn device on the user.
27. The user-worn device of claim 16 , wherein the physiological parameter comprises at least one of: methemoglobin, carboxyhemoglobin, or carbon monoxide.
28. The user-worn device of claim 16 , wherein the physiological parameter comprises total hemoglobin.
29. The user-worn device of claim 16 , wherein the LEDs and the photodiodes are arranged on a same side of the tissue of the user.