MULTI-STREAM DATA COLLECTION SYSTEM FOR NONINVASIVE MEASUREMENT OF BLOOD CONSTITUENTS
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 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 noninvasive device capable of producing a signal responsive to light attenuated by tissue at a measurement site, the device comprising:
an optical source configured to emit optical radiation at least at wavelengths between about 1600 nm and about 1700 nm; and
a plurality of photodetectors each configured to detect the optical radiation from said optical source after attenuation by said tissue of said measurement site and each output a respective signal stream responsive to said detected optical radiation.
2 . The device of claim 1 , wherein the optical source is configured to emit optical radiation at wavelengths from about 1600 to about 1670 nm.
3 . The device of claim 1 , wherein the optical source is configured to emit three wavelengths of optical radiation between about 1600 to about 1700 nm.
4 . The device of claim 3 , wherein the optical source is configured to emit optical radiation at three wavelengths about 30 nm apart.
5 . The device of claim 3 , wherein the optical source is configured to emit optical radiation at about 1610 nm, about 1645 nm, and about 1665 nm.
6 . The device of claim 1 , comprising a patient monitor capable of processing the plurality of output signal streams to determine output values for one or more physiological parameters.
7 . The device of claim 6 , wherein one of the one or more physiological parameters comprises glucose.
8 . A noninvasive, physiological sensor capable of outputting a signal responsive to a blood analyte present in a monitored patient, said sensor comprising:
a sensor housing;
an optical source positioned by said housing with respect to a tissue site of a patient when said housing is applied to the patient; and
photodetectors positioned by said housing with respect to said tissue site when said housing is applied to the patient with a variation in path length among at least some of the photodetectors from the optical source, the photodetectors configured to detect a sequence of optical radiation from said optical source after attenuation by tissue of said tissue site, said photodetectors each configured to output a respective signal stream responsive to said detected sequence of optical radiation and wherein an output signal responsive to one or more of the signal streams is usable to determine the blood analyte based at least in part on the variation in path length.
9 . The sensor of claim 8 , wherein the blood analyte comprises glucose, wherein the sensor comprises electronic circuitry configured to receive said signals responsive to said detected sequence of optical radiation and wherein said output signal is indicative of said glucose.
10 . The sensor of claim 8 , comprising a display coupled to the sensor housing and configured to display information indicating the blood analyte.
11 . The sensor of claim 6 , comprising a signal medium that is configured to connect to a processing device.
12 . The sensor of claim 8 , further comprising an interface configured to provide the signal to a device external to the sensor.
13 . The sensor of claim 12 , wherein the interface comprises at least one transimpedance amplifier configured to amplify the signal stream from the photodetectors.
14 . The sensor of claim 12 , wherein the interface comprises at least one switched capacitor circuit configured to convert said signal stream from the photodetectors into digital information.
15 . The sensor of claim 8 , wherein the housing comprises a shell constructed of material capable of reflecting at least some of the optical radiation back into the tissue site.
16 . The sensor of claim 6 , wherein the optical source comprises at least one set of sources comprising at least one light emitting diode and at least one super-luminescent light emitting diode.
17 . The sensor of claim 16 , wherein the light emitting diode is configured to transmit optical radiation at a wavelength of approximately 900 to approximately 1300 nm.
18 . The sensor of claim 16 , wherein the super-luminescent light emitting diode is configured to transmit optical radiation at a wavelength of approximately 1650 to approximately 1800 nm.
19 . The sensor of claim 8 , wherein the photodetectors are housed within optically separate compartments that reduce mixing of optical radiation from different regions of the tissue site.
20 . The sensor of claim 8 , further comprising an optical noise reducer capable of reducing ambient light from entering the tissue site.
21 . The sensor of claim 8 , further comprising a heat sink configured to dissipate heat from the sensor.
22 . The sensor of claim 8 , wherein the photodetectors are arranged in a special geometry.
23 . The sensor of claim 22 , wherein the special geometry comprises a substantially linear geometry.
24 . The sensor of claim 23 , wherein the special substantially linear geometry comprises substantially equal spacing.
25 . The sensor of claim 23 , wherein the special substantially linear geometry comprises substantially unequal spacing.
26 . The sensor of claim 23 , wherein the special substantially linear geometry comprises substantially logarithmic spacing.
27 . The sensor of claim 23 , wherein the special substantially linear geometry comprises substantially progressive spacing.
28 . The sensor of claim 22 , wherein the special geometry comprises a substantially grid geometry.
29 . A method of measuring an analyte based on multiple streams of optical radiation measured from a measurement site, said method comprising:
emitting a sequence of optical radiation pulses to the measurement site;
detecting at a first location a first stream of optical radiation from the measurement site;
detecting at least at one additional location different from the first location an additional stream of optical radiation from the measurement site; and
determining an output measurement value indicative of the analyte based on the detected streams of optical radiation.
30 . The method of claim 29 , wherein said analyte comprises glucose.
31 . The method of claim 29 , further comprising converting the detected streams of optical radiation into a digital signal including a respective stream for each location.
32 . The method of claim 29 , wherein said emitting comprises emitting light from at least one light emitting diode and at least one super-luminescent light emitting diode.
33 . The method of claim 29 , wherein said emitting comprises emitting at least one pulse at a wavelength of approximately 900 to approximately 1300 nm.
34 . The method of claim 29 , wherein said emitting comprises emitting at least one pulse at a wavelength of approximately 1650 to approximately 1800 nm.