SYSTEMS AND METHODS FOR OPTICAL MEASUREMENT OF ANALYTE CONCENTRATION

• US 20100024526A1
• Filed: 07/24/2009
• Published: 02/04/2010
• Est. Priority Date: 07/28/2008
• Status: Abandoned Application

• Current Assignee: Sensors For Medicine and Science Incorporated
• Original Assignee: Sensors For Medicine and Science Incorporated
• Inventors: Colvin, Arthur E. JR., DeHennis, Andrew
• Application Number:
  US12/508,727
• Publication Number:
  US 20100024526A1
• Time in Patent Office: Days
• US Class Current: 73/61.480
• CPC Class Codes: G01N 2021/6432 Quenching
• CPC Class Codes: G01N 2021/7786 Fluorescence
• CPC Class Codes: G01N 21/6428 Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" in vivo A61B5/00; immunoassay G01N33/53
• CPC Class Codes: G01N 21/643 non-biological material
• CPC Class Codes: G01N 21/77 by observing the effect on a chemical indicator
• CPC Class Codes: G01N 33/1806 biological or chemical oxygen demand (BOD or COD)

Abstract

A method and sensor for measuring the concentration of an analyte about radiantly excitable indicator molecules. A stimulus waveform is used to drive a radiant source. The indicator molecules are exposed to the radiant source. A response waveform is generated to represent photoluminescent radiation emitted by the indicator molecules. A phase difference between the stimulus waveform and the response waveform is a function of the concentration of the analyte that enables determining the analyte concentration.

Claims

1. A device for measuring analyte concentration comprising:

a sensor, said sensor comprising at least one indicator molecule in communication with a transducer;

a sensor interface module in communication with the sensor, wherein the sensor interface module comprises a microcontroller; and

wherein the sensor interface module facilitates time domain measurement of excitation emission of said at least one indicator molecule.

2. The device of claim 1, wherein the sensor is an optical sensor.

3. The device of claim 2, wherein the optical sensor comprises a radiation source.

4. The device of claim 3, wherein the radiation source comprises a light-emitting diode (LED).

5. The device of claim 4, wherein the LED comprises any one of a blue LED, violet LED, and red LED.

6. The device of claim 1, wherein the sensor interface module comprises an interface that enables communication between the sensor and the sensor interface module.

7. The device of claim 6, wherein the interface comprises an analog interface.

8. The device of claim 1, further comprising an external data system.

9. The device of claim 8, further comprising an interface that enables communications between the sensor interface module and the external data system.

10. The device of claim 1, wherein the at least one indicator molecule comprises any one of complex tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) perchlorate, a lanthanide-based indicator, and aromatic hydrocarbons.

11. The device of claim 10, wherein the lanthanide-based indicator comprises any one of europium and terbium complexes.

12. The device of claim 1, wherein the at least one indicator molecule is adjacent to the sensor.

13. The device of claim 1, wherein the sensor and the sensor interface module are capable of being provided on and communicate using a circuit board.

14. A method of measuring a concentration of an analyte comprising:

selecting a sensor;

providing an indicator molecule adjacent the sensor;

generating a stimulus waveform based on the analyte;

exciting the indicator molecule;

detecting a characteristic of the analyte based on its response characteristic to the indicator molecule excited; and

determining the analyte concentration.

15. The method of claim 14, wherein the generating a stimulus waveform comprises approximating a voltage waveform as a sine wave.

16. The method of claim 14, further comprising oversampling the stimulus waveform and the response waveform.

17. The method of claim 14, further comprising determining a phase delay between the stimulus waveform and the response waveform.

18. The method of claim 14, wherein the exciting the indicator molecules comprises irradiating the indicator molecules.

19. The method of claim 17, further comprising detecting a photoluminescent radiation of the indicator molecules.

20. The method of claim 14, wherein the selecting a sensor comprises selecting an optical sensor.

21. The method of claim 14, further comprising driving a radiant source with the stimulus waveform.

23. The device of claim 21, wherein the periodic digital signal has a frequency in a range of 9 kHz to 11 kHz.

24. The device of claim 21, wherein the microcontroller is further configured to serially communicate a parameter related to computation of analyte concentration with an apparatus external to the device.

25. The device of claim 21, wherein the device is in communication with an external device.

26. The device of claim 24, wherein the external device comprises a data collection system.

27. The device of claim 21, wherein the radiant source comprises a light-emitting diode.

28. The device of claim 21, wherein the microcontroller is further configured to output the periodic digital signal on the digital output bus as follows:

(a) the microcontroller waits to receive an instruction to take concentration data;

said instruction transmitted to a serial input port of the microcontroller;

(b) the microcontroller outputs a ramp signal on the digital output bus;

(c) the microcontroller outputs a signal representing a quantized sine wave at a predetermined frequency on the digital output bus; and

(d) the microcontroller sets the digital output bus to a standby value.

29. The device of claim 21, wherein the microcontroller is further configured to convert the phase difference to an analyte concentration value using a transfer function.

30. The device of claim 28, wherein the transfer function comprises dependent variables of any one of temperature, pressure, and humidity.

31. An analyte concentration sensor comprising:

the device of claim 21, wherein the device is adjacent an analyte.

32. The analyte concentration sensor according to claim 30, wherein the analyte is O₂, the radiant source comprises an LED, the photoelectric transducer comprises a photodiode, and the indicator molecules exhibit photoluminescent quenching in the presence of O₂.

34. The method of claim 32, wherein the analyte is O₂, the radiant source comprises an LED, the photoelectric transducer comprises a photodiode, and the indicator molecules exhibit photoluminescent quenching in the presence of O₂.

36. The method of claim 34, further comprising oversampling the stimulus waveform and the response waveform.

37. The method of claim 34, further comprising determining a phase delay between the stimulus waveform and the response waveform.

38. The method of claim 34, wherein the exciting the indicator molecules comprises irradiating the indicator molecules.

39. The method of claim 37, further comprising detecting a photoluminescent radiation of the indicator molecules.

40. The method of claim 34, wherein the selecting a sensor comprises selecting an optical sensor.

41. The method of claim 34, further comprising driving a radiant source with the stimulus waveform.

43. The method of claim 41, wherein the medium comprises any one of water, blood, and air.

22. A device for measuring an analyte concentration comprising:

a microcontroller configured to output a periodic digital signal of a predetermined frequency and compute a phase difference between a stimulus waveform and a response waveform;

a digital-to-analog converter operable to convert the periodic digital signal to a periodic voltage waveform;

a low pass filter operable to smooth the periodic voltage waveform and output the stimulus waveform;

a voltage-to-current converter operable to convert the stimulus waveform to a periodic current waveform and to drive a radiant source, wherein the radiant source radiates onto indicator molecules; and

a bandpass transimpedance amplifier operable to convert a current from a photoelectric transducer to the response waveform, wherein radiation from the indicator molecules is incident on a photoelectric transducer;

wherein the phase difference is a function of an analyte concentration local to the indicator molecules.

33. A method of determining the concentration of an analyte, the method comprising:

creating a periodic digital output signal on a microcontroller output;

converting the periodic digital output signal into a smoothed driver current waveform, said smoothed driver current waveform being of the same frequency as the periodic digital output signal;

driving a radiant source with said smoothed driver current, wherein radiation from the radiant source is incident on indicator molecules;

detecting radiant excitance of the indicator molecules with a photoelectric transducer, wherein the photoelectric transducer outputs a waveform of the same frequency as the smoothed driver current waveform; and

measuring a phase difference between the smoothed driver current waveform and the outputted photoelectric transducer waveform;

wherein the phase difference correlates to an analyte concentration local to the indicator molecules.

35. A method of measuring a concentration of an analyte comprising:

selecting a sensor;

providing an indicator molecule adjacent the sensor;

generating a stimulus waveform based on the analyte;

exciting the indicator molecule;

detecting a characteristic of the analyte based on its response characteristic to the indicator molecule excited; and

determining the analyte concentration.

42. A method of determining a presence of oxygen within a medium, comprising:

selecting an oxygen sensor;

providing the sensor with an indicator molecule;

locating the sensor within a medium;

transmitting a phase modulated signal to the sensor from a sensor interface module;

determining a rate of change of the phase modulated signal; and

determining a concentration of oxygen within the medium.