Wearable devices using near-infrared light sources
A wearable device includes a measurement device having light emitting diodes (LEDs) measuring a physiological parameter. The measurement device modulates the LEDs to generate an optical beam having a near-infrared wavelength between 700-2500 nanometers. Lenses receive and deliver the optical beam to tissue, which reflects the optical beam to a receiver having spatially separated detectors coupled to analog-to-digital converters configured to generate receiver outputs. The receiver captures light while the LEDs are off, and reflected light from the tissue while the LEDs are on, to generate first and second signals, respectively. Signal-to-noise ratio is improved by differencing the first and second signals and by differencing the receiver outputs. The measurement device further improves signal-to-noise ratio of the reflected optical beam by increasing light intensity of the LEDs relative to an initial light intensity. The measurement device generates an output signal representing a non-invasive measurement on blood contained within the tissue.
1. A wearable device, comprising:
a measurement device including a light source comprising a plurality of light emitting diodes (LEDs) for measuring one or more physiological parameters, the measurement device configured to generate, by modulating at least one of the LEDs having an initial light intensity, an optical beam having a plurality of optical wavelengths, wherein at least a portion of the optical beam includes a near-infrared wavelength between 700 nanometers and 2500 nanometers;
the measurement device comprising one or more lenses configured to receive and to deliver at least a portion of the optical beam to tissue, wherein the tissue reflects at least a portion of the optical beam delivered to the tissue;
the measurement device further comprising a receiver, the receiver having a plurality of spatially separated detectors and one or more analog to digital converters coupled to the spatially separated detectors, the one or more analog to digital converters configured to generate at least two receiver outputs, the receiver configured to:
capture light while the LEDs are off and convert the captured light into a first signal and
capture light while at least one of the LEDs is on and to convert the captured light into a second signal, the captured light including at least a portion of the optical beam reflected from the tissue;
the measurement device configured to improve a signal-to-noise ratio of the optical beam reflected from the tissue by differencing the first signal and the second signal and by differencing the two receiver outputs;
the measurement device configured to further improve the signal-to-noise ratio of the optical beam reflected from the tissue by increasing the light intensity relative to the initial light intensity from at least one of the LEDs;
the measurement device further configured to generate an output signal representing at least in part a non-invasive measurement on blood contained within the tissue, wherein the output signal is generated at least in part by using a Fourier transform of signals from the receiver including at least one of the first and second signals and signals from the at least two receiver outputs; and
wherein the receiver further comprises one or more spectral filters positioned in front of at least some of the plurality of spatially separated detectors.
2. The wearable device of claim 1 , wherein the measurement device is adapted to be placed on a wrist of a user.
3. The wearable device of claim 1 , wherein the measurement device is adapted to be placed on an ear of a user.
4. The wearable device of claim 1 , wherein
the wearable device is configured to communicate with a smart phone or tablet, the smart phone or tablet comprising a wireless receiver, a wireless transmitter, a display, a voice input module, a speaker, and a touch screen, the smart phone or tablet configured to receive and to process at least a portion of the output signal, wherein the smart phone or tablet is configured to store and display the processed output signal, wherein at least a portion of the processed output signal is configured to be transmitted over a wireless transmission link.
5. The wearable device of claim 1 , wherein the receiver is configured to be synchronized to the modulation of the at least one of the LEDs.
6. The wearable device of claim 1 , wherein the receiver is located a first distance from a first one of the LEDs and a different distance from a second one of the LEDs such that the receiver can capture a third signal from the first LED and a fourth signal from the second LED, and wherein the output signal is generated in part by comparing the third and fourth signals.
7. The wearable device of claim 1 , wherein at least one LED emits at a first wavelength and at least another LED emits at a second wavelength, and wherein the first wavelength has a first penetration depth into the tissue and wherein the second wavelength has a second penetration depth into the tissue different from the first penetration depth, and wherein the output signal is generated in part by comparing the reflected light at the first wavelength with the reflected light at the second wavelength.
8. A wearable device, comprising:
a measurement device including a light source comprising a plurality of light emitting diodes (LEDs) for measuring one or more physiological parameters, the measurement device configured to generate, by modulating at least one of the LEDs having an initial light intensity, an optical beam having a plurality of optical wavelengths, wherein at least a portion of the plurality of optical wavelengths is a near-infrared wavelength between 700 nanometers and 2500 nanometers;
the measurement device comprising one or more lenses configured to receive and to deliver a portion of the optical beam to tissue, wherein the tissue reflects at least a portion of the optical beam delivered to the tissue, and wherein the measurement device is adapted to be placed on a wrist or an ear of a user;
the measurement device further comprising a receiver, the receiver having a plurality of spatially separated detectors and one or more analog to digital converters coupled to the spatially separated detectors, the one or more analog to digital converters configured to generate at least two receiver outputs;
the measurement device configured to improve a signal-to-noise ratio of the optical beam reflected from the tissue by differencing the two receiver outputs;
the measurement device configured to further improve the signal-to-noise ratio of the optical beam reflected from the tissue by increasing the light intensity relative to the initial light intensity from at least one of the LEDs;
the measurement device further configured to generate an output signal representing at least in part a non-invasive measurement on blood contained within the tissue, wherein the output signal is generated at least in part by using a Fourier transform of a signal resulting from differencing signals from the at least two receiver outputs; and
wherein the receiver further comprises one or more spectral filters positioned in front of at least some of the plurality of spatially separated detectors.
9. The wearable device of claim 8 , wherein at least one LED emits at a first wavelength and at least another LED emits at a second wavelength, and wherein the first wavelength has a first penetration depth into the tissue and wherein the second wavelength has a second penetration depth into the tissue different from the first penetration depth.
10. The wearable device of claim 9 , wherein the output signal is generated in part by comparing the reflected light at the first wavelength with the reflected light at the second wavelength.
11. The wearable device of claim 8 , wherein the receiver is further configured to:
capture light while the LEDs are off and convert the captured light into a first signal and
capture light while at least one of the LEDs is on and convert the captured light into a second signal, the captured light including at least a portion of the optical beam reflected from the tissue;
the measurement device configured to further improve a the signal-to-noise ratio of the optical beam reflected from the tissue by differencing the first signal and the second signal.
12. The wearable device of claim 8 , wherein
the wearable device is configured to communicate with a smart phone or tablet, the smart phone or tablet comprising a wireless receiver, a wireless transmitter, a display, a voice input module, a speaker, and a touch screen, the smart phone or tablet configured to receive and to process at least a portion of the output signal, wherein the smart phone or tablet is configured to store and display the processed output signal, wherein at least a portion of the processed output signal is configured to be transmitted over a wireless transmission link.
13. The wearable device of claim 8 , wherein the receiver is configured to be synchronized to the modulation of the at least one of the LEDs.
14. The wearable device of claim 8 , wherein the receiver is located a first distance from a first one of the LEDs and a different distance from a second one of the LEDs such that the receiver can capture a third signal from the first LED and a fourth signal from the second LED, and wherein the output signal is generated in part by comparing the third and fourth signals.
15. A wearable device, comprising:
a measurement device including a light source comprising a plurality of light emitting diodes (LEDs) for measuring one or more physiological parameters, the measurement device configured to generate, by modulating at least one of the LEDs having an initial light intensity, an optical beam having a plurality of optical wavelengths, wherein at least a portion of the plurality of optical wavelengths is a near-infrared wavelength between 700 nanometers and 2500 nanometers;
the measurement device comprising one or more lenses configured to receive and to deliver a portion of the optical beam to tissue, wherein the tissue reflects at least a portion of the optical beam delivered to the tissue, and wherein the measurement device is adapted to be placed on a wrist or an ear of a user;
the measurement device further comprising a receiver, the receiver having a plurality of spatially separated detectors and one or more analog to digital converters coupled to the spatially separated detectors, the one or more analog to digital converters configured to generate at least two receiver outputs, the receiver configured to:
capture light while the LEDs are off and convert the captured light into a first signal and
capture light while at least one of the LEDs is on and convert the captured light into a second signal, the captured light including at least a portion of the optical beam reflected from the tissue;
the measurement device configured to improve a signal-to-noise ratio of the optical beam reflected from the tissue by differencing the first signal and the second signal and by differencing the two receiver outputs;
the measurement device configured to further improve the signal-to-noise ratio of the optical beam reflected from the tissue by increasing the light intensity relative to the initial light intensity from at least one of the LEDs;
the measurement device further configured to generate an output signal representing at least in part a non-invasive measurement on blood contained within the tissue, wherein the output signal is generated at least in part by using a Fourier transform of signals from the receiver including at least one of the first and second signals and signals from the at least two receiver outputs; and
wherein the receiver further comprises one or more spectral filters positioned in front of at least some of the plurality of spatially separated detectors.
16. The wearable device of claim 15 , wherein at least one LED emits at a first wavelength and at least another LED emits at a second wavelength, and wherein the first wavelength has a first penetration depth into the tissue and wherein the second wavelength has a second penetration depth into the tissue different from the first penetration depth.
17. The wearable device of claim 16 , wherein the output signal is generated in part by comparing the reflected light at the first wavelength with the reflected light at the second wavelength.
18. The wearable device of claim 15 , wherein the receiver is configured to be synchronized to the modulating of the at least one of the LEDs.
19. The wearable device of claim 15 , wherein the receiver is located a first distance from a first one of the LEDs and a different distance from a second one of the LEDs such that the receiver can capture a third signal from the first LED and a fourth signal from the second LED, and wherein the output signal is generated in part by comparing the third and fourth signals.