Finger receptor

• US 5,429,128 A
• Filed: 02/24/1993
• Issued: 07/04/1995
• Est. Priority Date: 08/29/1990
• Status: Expired due to Term

• Current Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Original Assignee: CME Telemetrix, Inc.
• Inventors: Cadell, Theodore E., MacHattie, Donald B.
• Primary Examiner(s): SYKES, ANGELA D
• Assistant Examiner(s): Green, Brian M.
• Application Number:
  US08/043,464
• Time in Patent Office: 860 Days
• Field of Search: 128/632, 128/633, 128/637, 128/665, 128/667, 128/687, 128/689
• US Class Current: 600/310
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure

Abstract

A finger receptor is used with a non-invasive monitoring device to determine non-invasively the concentration of known constituents in blood or tissue. The receptor has a channel for receiving a finger of a user. The channel has a light entrance and a light exit so that light can be passed from a light source through a finger located in the channel in a direction generally normal to the finger. Extraneous light is excluded and the finger is held in position by a spring-mounted roller. The receptor has sensing means to determine when a finger has been properly positioned in the channel. Previous devices are not capable of achieving repeatable results to a sufficient degree to replace invasive methods of testing.

Claims

1. A finger receptor for use with a non-invasive monitoring device, said receptor being used with a light source to receive a finger of a user, said receptor comprising a base containing an elongated channel sized to receive a finger, said channel having an opening to receive said finger and two sides with a light path entrance on one side and a light path exit on another side, said entrance and exit being sized and located so that at least some of the light passing through said entrance is received at said exit, said channel being shaped so that a finger properly inserted into said channel completely fills a zone of said channel located between said entrance and exit so that no light from said entrance can reach said exit without passing through said finger, light from said light source forming an optical path from said entrance to said exit, with sensing means to determine when said finger is properly positioned in said channel.

2. A receptor as claimed in claim 1 wherein said zone is bounded by the entrance and exit and an inner surface of said channel extending between said entrance and said exit.

3. A receptor as claimed in claim 2 wherein there are means to reduce a level of intensity of said light source when a reference measurement is being taken using said monitoring device.

4. A receptor as claimed in claim 1 wherein the channel has a cross-sectional shape with a bottom that curves smoothly to a first side and a second side, said first side having said entrance located therein and being relatively steep, said second side having said exit located therein and having a gentle slope compared to said first side.

5. A receptor as claimed in claim 4 wherein there are means for moving the optical path relative to said finger as light from said light source is transmitted along said light path.

6. A receptor as claimed in claim 1 wherein there are pressure means to gently force the finger into an appropriate position when the finger is inserted into the channel, the pressure from said pressure means being of sufficient strength to slow blood flow in the finger but not to stop it and to concentrate blood adjacent to the entrance and exit.

7. A receptor as claimed in claim 5 wherein the means for moving the optical path relative to said finger is a movable lens mounted to the base in front of said light path entrance.

8. A receptor as claimed in claim 7 wherein said lens is mounted on an arm that is connected to a motor, said arm being movable and moving said lens relative to said finger when said monitoring device is in operation.

9. A receptor as claimed in claim 8 wherein there are means to reduce a level of intensity of said light source when a reference measurement is being taken using said monitoring device.

10. A receptor as claimed in claim 9 wherein the means to reduce the level of light intensity is a filter mounted between said light source and said monitoring device.

11. A receptor as claimed in claim 10 wherein the filter is mounted to the same arm as said lens but is offset from said lens so that the lens is located between said light source and said finger when the filter is not located to reduce the light intensity and the filter is located to reduce said light intensity from said receptor when said lens is not located between said light source and said finger.

12. A receptor as claimed in claim 1 wherein the sensing means is connected to automatically activate said monitoring device when said finger is properly positioned in said channel.

13. A receptor as claimed in claim 1 wherein there is a support connected to the receptor and located outside of said channel to support a hand of said user so that movement of the finger of said hand during operation of the monitoring device is minimized.

14. A receptor as claimed in claim 3 wherein the means to reduce the level of light intensity is a filter located within a path of said light.

15. A receptor as claimed in claim 3 wherein the means to reduce the level of light intensity are reflection means by which some of said light can be monitored.

16. A receptor as claimed in any one of claims 1, 2 or 3 wherein the channel is placed at an angle of approximately 30°

from horizontal.

17. A receptor as claimed in claim 15 wherein the reflection means are a series of reflectors that reflect some of the light from the light source around said receptor so that the amount of light received by the monitoring device is reduced in intensity.

18. A receptor as claimed in any one of claims 1, 2 or 3 wherein there is a plunger slidably mounted in said channel, said plunger being spring-loaded and biased towards said opening so that said plunger is pushed away from said opening by said finger when said finger is inserted in said plunger triggering said sensor means when said finger is properly positioned in said opening.

19. A receptor as claimed in claim 6 wherein the pressure means is a roller rotatably mounted on a torsion spring-loaded armature that is biased toward said channel, said roller being located to contact said finger as it is being inserted and when the finger is located in the channel.

20. A receptor as claimed in claim 1 wherein the light entrance into said channel has a circular shape and the light exit from said channel has an oblong shape.

21. A receptor as claimed in claim 20 wherein the entrance converges through said base towards said channel and the exit has a constant size from said channel through said base.

22. A receptor as claimed in claim 21 wherein the entrance has side walls and converges in three steps, said side walls of the entrance being parallel to one another.

23. A receptor as claimed in any one of claims 1, 2 or 3 wherein the finger of the user has a finger bone and the channel is shaped so that the light path extending between the entrance and exit is located below-the finger bone.