Method and device for correcting optical signals
First Claim
1. A method, comprising:
- sending a first generated light within an excitation wavelength range from a first light emitting diode (LED) of an optical device disposed on a skin of a mammalian body, the first generated light sent through tissue of the mammalian body to an implant embedded in the tissue, the implant configured to absorb light within the excitation wavelength range and fluoresce to emit an analyte-dependent optical signal within an emission wavelength range in response to absorbing light within the excitation wavelength range;
receiving, with at least one detector of the optical device disposed on the skin of the mammalian body and in response to the first generated light being sent through the tissue, a first optical signal emitted from the implant embedded in the tissue within the emission wavelength range;
calculate, with a processor of the optical device disposed on the skin of the mammalian body, an initial value indicative of a concentration of the analyte based on the first optical signal;
sending, from the optical device disposed on the skin of the mammalian body and into the tissue, a second generated light, the second generated light sent from a second LED pre-configured to emit light within the emission wavelength range;
receiving, with the at least one detector and in response to the second generated light, a second optical signal emitted from the tissue within the emission wavelength range;
calculating, with the processor, a correction factor based on the second optical signal, the correction factor indicative of background within the emission wavelength range; and
calculating, with the processor, the concentration of the analyte by applying the correction factor to the initial value indicative of the concentration of the analyte.
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Abstract
An optical device is used to monitor an implant embedded in the tissue of a mammal (e.g., under the skin). The implant receives excitation light from the optical device and emits light that is detected by the optical device, including an analyte-dependent optical signal. Scatter and absorption properties of tissue change over time due to changes in hydration, blood perfusion and oxygenation. The optical device has an arrangement of light sources, filters and detectors to transmit excitation light within excitation wavelength ranges and to measure emitted light within detection wavelengths. Changes in scattering and absorption of light in the tissue, such as diffuse reflectance, are monitored. The light sources, filters and detectors may also be used to monitor autofluorescence in the tissue to correct autofluorescence background.
225 Citations
20 Claims
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1. A method, comprising:
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sending a first generated light within an excitation wavelength range from a first light emitting diode (LED) of an optical device disposed on a skin of a mammalian body, the first generated light sent through tissue of the mammalian body to an implant embedded in the tissue, the implant configured to absorb light within the excitation wavelength range and fluoresce to emit an analyte-dependent optical signal within an emission wavelength range in response to absorbing light within the excitation wavelength range; receiving, with at least one detector of the optical device disposed on the skin of the mammalian body and in response to the first generated light being sent through the tissue, a first optical signal emitted from the implant embedded in the tissue within the emission wavelength range; calculate, with a processor of the optical device disposed on the skin of the mammalian body, an initial value indicative of a concentration of the analyte based on the first optical signal; sending, from the optical device disposed on the skin of the mammalian body and into the tissue, a second generated light, the second generated light sent from a second LED pre-configured to emit light within the emission wavelength range; receiving, with the at least one detector and in response to the second generated light, a second optical signal emitted from the tissue within the emission wavelength range; calculating, with the processor, a correction factor based on the second optical signal, the correction factor indicative of background within the emission wavelength range; and calculating, with the processor, the concentration of the analyte by applying the correction factor to the initial value indicative of the concentration of the analyte. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method, comprising:
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sending a first generated light from at least one light source disposed within a case of an optical device through tissue of a mammalian body to an implant embedded in the tissue, the at least one light source pre-configured to emit the first generated light within an excitation wavelength range, the implant configured to absorb light within the excitation wavelength range and emit an analyte-dependent optical signal within an emission wavelength range in response to absorbing light within the excitation wavelength range; measuring, in response to the first generated light with at least one detector disposed within the case of the optical device, a first optical signal emitted from the implant embedded in the tissue within the emission wavelength range to produce a value indicative of a concentration of the analyte; sending a second generated light within the excitation wavelength range into the tissue from the at least one light source; determining a value indicative of tissue autofluorescence based on a second optical signal emitted from the tissue within the emission wavelength range in response to the second generated light, the second light source spaced apart from the first light source within the case such that the second optical signal travels a light path that is spaced laterally from the implant when the first light source sends the first generated light to the implant such that the second optical signal does not include a significant contribution from the implant; calculating a correction factor using the value indicative of tissue autofluorescence; and calculating the concentration of the analyte by applying the correction factor to the value indicative of the concentration of the analyte. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification