Diode detection circuit

• US 6,668,183 B2
• Filed: 09/11/2001
• Issued: 12/23/2003
• Est. Priority Date: 09/11/2001
• Status: Expired due to Term

• Current Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Original Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Inventors: Light, Scott James Charles, Hicks, Christopher Anthony, Norris, Mark A., Huiku, Matti Veli Tapani
• Primary Examiner(s): Winakur, Eric F.
• Assistant Examiner(s): McCrosky, David J.
• Application Number:
  US09/953,138
• Publication Number:
  US 20030050545A1
• Time in Patent Office: 833 Days
• Field of Search: 600/310, 600/322, 600/323, 600/331, 600/500-507
• US Class Current: 600/331
• CPC Class Codes: A61B 2562/08 Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

A photoplethysmographic system and method is provided to identify compatible sensors to monitors and/or for determining sensor attributes. The improved system includes a signal generation means for providing an interrogation signal, an identifying means coupled between a first and second sensor terminal operable to produce multiple outputs upon application of the interrogation signal in two modes of operation, and a processor to interpret the outputs. When the interrogation signal is applied to a sensor terminal in a first mode, a first output is obtained. Upon applying the same interrogation signal to the sensor terminal in a second mode, a second output is obtained. The first and second outputs may then be utilized by the processor comprising, for example, a photoplethysmographic monitor to yield enhanced sensor information. The disclosed method may be carried out utilizing the inventive photoplethysmographic system.

Claims

1. A photoplethysmographic system for use in determining at least one data value corresponding with a photoplethysmographic sensor comprising:

signal generation means for generating at least one interrogation signal in each of a first mode of operation and a second mode of operation;

sensor identifying means for receiving said at least one interrogation signal, wherein a first polarity is established at a first sensor terminal throughout said first mode of operation and an opposite second polarity is established at the first terminal throughout said second mode of operation, and wherein said identifying means produces a first output in said first mode of operation and a second output in said second mode of operation; and

processor means for employing said first and second outputs to determine at least a first data value corresponding with said sensor.

2. A photoplethysmographic system as recited in claim 1, wherein said signal generation means comprises means for establishing said first and second modes of operation.

3. A photoplethysmographic system as recited in claim 2, wherein said means for establishing comprises:

a power supply for providing at least one said interrogation signal having said first polarity at said first terminal;

an electrical storage means for storing an electrical potential from said power supply; and

a switching means for selectively discharging said electrical storage means to produce said opposite second polarity at said first terminal.

4. A photoplethysmographic system as recited in claim 3, wherein said power supply comprises a steady state power source.

5. A photoplethysmographic system as recited in claim 4, wherein said steady state power source comprises a voltage divider for providing said constant voltage.

6. A photoplethysmographic system as recited in claim 3, wherein said electrical potential has an equal voltage and opposite polarity of said power supply.

7. A photoplethysmographic system as recited in claim 6, wherein said electrical storage means comprises a capacitor.

8. A photoplethysmographic system as recited in claim 3, wherein said switching means is selectively activable to change said system from said first mode of operation to said second mode of operation for a predetermined time.

9. A photoplethysmographic system as recited in claim 8, further comprising a processing means for selectively activating said switching means.

10. A photoplethysmographic system as recited in claim 2, wherein said signal generating means is located at least partially in a cable connecting said photoplethysmographic sensor to said processing means.

11. A photoplethysmographic system as recited in claim 2, wherein said signal generating means is located at least partially in said photoplethysmographic sensor.

12. A photoplethysmographic system as recited in claim 2, wherein said signal generating means is located at least partially in a photoplethysmographic monitor.

13. A photoplethysmographic system as recited in claim 1, wherein said identifying means comprises a plurality of electrical components electrically interconnected between said first sensor terminal and second sensor terminals.

14. A photoplethysmographic system as recited in claim 13, wherein at least one of said plurality of electrical components is an active component.

15. A photoplethysmographic system as recited in claim 1, wherein said first output comprises at least a first response to said interrogation signal as established at said first terminal in said first mode of operation.

16. A photoplethysmographic system as recited in claim 15, wherein said first mode of operation comprises a steady state mode of operation.

17. A photoplethysmographic system as recited in claim 15, wherein said second mode of operation comprises a transient mode of operation.

18. A photoplethysmographic system as recited in claim 1, wherein said second output comprises at least a first response to said interrogation signal as established at said first terminal in said second mode of operation.

19. A photoplethysmographic system as recited in claim 18, wherein said second mode of operation takes place over a predetermined time and said second output comprises a plurality of said responses over said predetermined time.

20. A photoplethysmographic system as recited in claim 19, wherein said second output comprises a time profile of said plurality of said responses over said predetermined time.

21. A photoplethysmographic system as recited in claim 18, wherein said second mode of operation comprises a transient mode of operation.

22. A photoplethysmographic system as recited in claim 1, wherein said processing means is operable to compare said first and second outputs to stored data values to determine data particular to said sensor.

23. A photoplethysmographic system as recited in claim 1, wherein said processing means comprises a photoplethysmographic monitor.

24. The photoplethysmographic system as recited in claim 1, wherein said first and second outputs are different.

25. The photoplethysmographic system as recited in claim 1, wherein a positive voltage is established at said first terminal throughout one of said first and second modes and a negative voltage is established at said first terminal throughout the other of said first and second modes.

26. The photoplethysmographic system as recited in claim 25, wherein at least one of said positive and negative voltages comprises a transient voltage during at least a portion of the respective said mode.

27. The photoplethysmographic system as recited in claim 1, wherein said interrogation signal establishes a current flow in a first direction relative to said first sensor terminal throughout said first mode and wherein said interrogation signal establishes a current flow in a second direction relative to said first sensor terminal throughout said second mode.

28. The photoplethysmographic system as recited in claim 27, wherein a magnitude of said current flow is transient during at least a portion of one of said first and second modes.

29. The photoplethysmographic system as recited in claim 1, wherein said sensor identifying means is interconnected between said first sensor terminal and a second sensor terminal.

30. The photoplethysmographic system as recited in claim 29, wherein said processor means is operative to identify changes in said at least one interrogation signal as applied across said first and second terminals in said first and second modes of operation.

31. The photoplethysmographic system as recited in claim 29, wherein at least one of said first and second outputs comprises a voltage drop between said first and second terminals.

32. The photoplethysmographic system as recited in claim 31, wherein the other of said first and second outputs is substantially the same as said at least one interrogation signal.

33. A method to determine at least one data value from a photoplethysmographic sensor comprising the steps of:

applying an interrogation signal having a first polarity throughout a first mode of operation to a photoplethysmographic sensor with an identifying means between at least a first and second terminal, wherein a first output is obtained in said first mode of operation;

reversing the polarity of said interrogation signal to apply an opposite second polarity to said photoplethysmographic sensor identification means throughout a second mode of operation, wherein a second output is obtained in said second mode of operation; and

employing said first and second outputs to determine at least one data value corresponding with said photoplethysmographic sensor.

34. The method of claim 33, wherein said step of applying an interrogation signal comprises applying a steady state electrical signal to said identifying means.

35. The method of claim 33, wherein obtaining said first output comprises measuring a steady state response of said interrogation signal as applied to said identifying means.

36. The method of claim 33, wherein said step of reversing further comprises:

supplying an interrogation signal with said first polarity to said first terminal;

charging an energy storage means with said interrogation signal to store an electrical potential; and

utilizing said electrical potential to selectively reverse said interrogation signal polarity as applied to said first terminal for a predetermined time to establish said second opposite polarity, wherein at least one said second output is obtained during said predetermined time.

37. The method of claim 36, wherein obtaining said second output comprises measuring a transient response of said interrogation signal as applied to said identifying means during said predetermined time.

38. The method of claim 37, wherein measuring said transient response comprises taking a plurality of measurements during said predetermined time.

39. A method as recited in claim 33, said employing step comprising:

comparing at least one of first and second outputs with at least a first predetermined data range.

40. A method as recited in claim 33, wherein when at least one of said first and second outputs is outside of a first and second predetermined data range, respectively, said method further comprises at least one of the following steps:

providing an output signal to a user to indicate that the photoplethysmographic sensor is outside at least one of said first and second predetermined data ranges; and

,

disabling the photoplethysmographic monitor for use with the interconnected photoplethysmographic sensor.

41. A method as recited in claim 40, further comprising:

displaying a visual message to a user at said photoplethysmographic monitor indicating one of;

that at least one of said first and second outputs associated with said photoplethysmographpic sensor is outside of at least one of said first and second predetermined data ranges; and

that said photoplethysmographic monitor is disabled.

42. A method as recited in claim 33, wherein when said first output is within a first predetermined data range and said second output is within said second predetermined data range, said method further comprises:

utilizing said photoplethysmographic sensor to obtain an identification signal indicative of light absorption by the tissue-under-test; and

,

employing said detector signal to obtain a concentration value for at least one blood analyte.

43. A method as recited in claim 33, said employing step including:

utilizing at least one of said first output and second output to select one of a plurality of a calibration values for use with said sensor.

44. The method of claim 33, wherein obtaining said outputs comprises obtaining first and second outputs wherein said outputs are different.

45. The method of claim 33, wherein obtaining said first and second outputs each comprises measuring a change in said interrogation signal across said first and second terminals.

46. The method of claim 45, wherein measuring a change comprises measuring a voltage change across said first and second terminals for at least one of said first and second outputs.

47. A photoplethysmographic system for use in determining at least one data value corresponding with a photoplethysmographic sensor comprising:

signal generation means for generating at least one interrogation signal in each of a first mode of operation and a second mode of operation;

sensor identifying means for receiving said at least one interrogation signal across first and second terminals in each of said first and second modes of operation, said sensor identifying means being operable to produce first and second outputs in said first and second modes of operation, respectively, wherein one of said first and second outputs is substantially the same as said at least one interrogation signal; and

processor means for employing said first and second outputs to determine at least a first data value corresponding with said sensor.

48. The photoplethysmographic system as recited in claim 47, wherein said signal generation means establishes a first polarity across said first and second terminals in said first mode of operation and establishes an opposite second polarity across said first and second terminals in said second mode of operation.

49. The photoplethysmographic system as recited in claim 48, wherein said first polarity is maintained throughout said first mode of operation and said opposite second polarity is maintained throughout said second mode of operation.

50. The photoplethysmographic system as recited in claim 47, wherein said sensor identifying means comprises parallel electrical paths between said first and second terminals.

51. The photoplethysmographic system as recited in claim 50, wherein one of said parallel electrical paths contains a unidirectional electrical component.

52. The photoplethysmographic system as recited in claim 51, wherein said unidirectional electrical component comprises a diode.

53. The photoplethysmographic system as recited in claim 51, wherein the other of said parallel electrical paths comprises an electrical component operable to produce a voltage drop in response to axis applied signal between said first and second terminals.

54. The photoplethysmographic system as recited in claim 51, wherein said processing means is further operative to compare at least one of said first and second outputs with at least a first set of predetermined data values.

55. The photoplethysmographic system as recited in claim 54, wherein upon determining at least one of said first and second output is outside of at least one range of said predetermined data values, said processor being further operative to:

provide an output signal to a user to indicate that the photoplethysmographic sensor is outside said range of predetermined data values; and

,

disable the photoplethysmographic monitor for use with the interconnected photoplethysmographic sensor.