System and single-channel biosensor for and method of determining analyte value
Some embodiments described herein relate to a sensor that includes an analyte-sensing dye and a reference dye. The analyte-sensing dye can be configured to emit an analyte-dependent optical signal in the presence of an analyte. Similarly stated, the intensity and/or duration of the analyte-dependent optical signal can be modulated by a quantity and/or concentration of the analyte in the environment of the sensor. The reference dye can be configured to emit an analyte-independent optical signal. The analyte-dependent optical signal and the analyte-independent optical signal have an analyte-dependent spectrum and an analyte-independent spectrum, respectfully. The analyte-dependent optical spectrum and the analyte-independent spectrum can be the same, substantially the same, and/or overlapping. The analyte-dependent optical signal can have a duration of lifetime that is shorter than a duration or lifetime of the analyte-independent optical signal.
1. A system, comprising:
a sensor, including:
an analyte-sensing dye configured to emit an analyte-dependent optical signal in the presence of an analyte, the analyte-dependent optical signal having an analyte-dependent spectrum and a first duration; and
a reference dye configured to emit an analyte-independent optical signal having an analyte-independent spectrum and a second duration, the analyte-dependent spectrum and the analyte-independent spectrum overlapping, the second duration exceeding the first duration; and
a reader, including:
a light source configured to emit an illumination signal configured to excite the analyte-sensing dye and the reference dye, the analyte-sensing dye and the reference dye configured to emit the analyte-dependent optical signal and the analyte-independent optical signal, respectively, in response to being excited by the illumination signal;
a detector configured to detect the analyte-dependent optical signal and the analyte-independent optical signal;
an amplifier having variable gain, the amplifier configured to process a signal received during a first time period that is associated with the analyte-dependent optical signal with a first gain to produce a first processed signal, the amplifier configured to process a signal received during a second time period that is associated with the analyte-independent signal with a second gain different from the first gain to produce a second processed signal, the second time period being after the first time period; and
a processor configured to determine at least one of a concentration or a quantity of the analyte based on a ratio of the first processed signal and the second processed signal.
2. The system of claim 1 , wherein the illumination signal has a spectrum configured to simultaneously excite the analyte-sensing dye and the reference dye.
3. The system of claim 1 , wherein the light source is a single light source configured to emit a single illumination signal configured to simultaneously excite the analyte-sensing dye and the reference dye.
4. The system of claim 1 , wherein the detector is a single detector configured to detect each of the analyte-dependent optical signal and the analyte-independent optical signal.
5. The system of claim 1 , wherein:
the sensor is configured to be implanted in tissue of a body; and
the reader is configured to be disposed outside the body, the sensor and the reader not being physically coupled.
6. The system of claim 1 , wherein the reader includes a filter disposed between the light source and the sensor, all light emitted from the reader passing through the filter.
7. The system of claim 1 , wherein the reader includes a filter disposed between the detector and the sensor, all light entering the reader passing through the filter.
8. The system of claim 1 , wherein the second duration is at least an order of magnitude greater than the first duration.
9. The system of claim 1 , wherein the reference dye is configured to emit the analyte-independent optical signal with an intensity that is insensitive to a chemical environment in which the reference dye is disposed.
10. The system of claim 1 , wherein the first duration is less than 50 nanoseconds.
11. The system of claim 1 , wherein the second duration is greater than 1 microsecond.
12. The system of claim 1 , wherein:
the first duration is less than 50 nanoseconds; and
the second duration is greater than 1 microsecond.
13. The system of claim 1 , wherein the analyte is at least one of oxygen, glucose, lactate, carbon dioxide, H + , or OH − .
14. The system of claim 1 , wherein:
the analyte-sensing dye is a first analyte-sensing dye configured to emit a first analyte-dependent optical signal in the presence of a first analyte; and
the analyte-dependent optical signal is a first analyte-dependent optical signal having a first analyte-dependent spectrum, the system further comprising:
a second analyte-sensing dye configured to emit a second analyte-dependent optical signal in the presence of a second analyte, the second analyte-dependent optical signal having a second analyte-dependent spectrum different from the first analyte-dependent spectrum.
15. The system of claim 1 , wherein the sensor is configured to be implanted in tissue of a body.
16. The system of claim 1 , wherein:
the sensor is configured to be implanted in tissue of a body; and
the analyte-sensing dye is configured to emit the analyte-dependent optical signal in the presence of the analyte within blood or interstitial fluid of the tissue.
17. A method, comprising:
illuminating a sensor with an illumination signal to simultaneously excite an analyte-dependent dye and an analyte-independent dye such that the analyte-dependent dye emits an analyte-dependent optical signal having a first duration simultaneously with the analyte-independent dye emitting an analyte-independent optical signal having a second duration longer than the first duration, a spectrum of the analyte-independent optical signal overlapping a spectrum of the analyte-dependent optical signal;
detecting the analyte-dependent optical signal during a first time period;
processing a signal associated with the analyte-dependent optical signal with an amplifier at a first gain;
detecting an analyte-independent optical signal during a second time period after the first time period;
processing a signal associated with the analyte-independent optical signal with the amplifier at a second gain higher than the first gain; and
determining at least one of a quantity or a concentration of an analyte based on a ratio of the signal associated with the analyte-dependent optical signal processed with the first gain and the signal associated with the analyte-independent optical signal processed with the second gain.
18. The method of claim 17 , wherein the illumination signal is emitted from is a single light source configured to emit a single illumination signal configured to simultaneously excite the analyte-sensing dye and the reference dye.
19. The method of claim 17 , wherein a spectrum of the analyte-dependent optical signal is the same as a spectrum of the analyte-independent optical signal.
20. The method of claim 17 , wherein the analyte-dependent optical signal and the analyte-independent optical signal are detected by the same detector.