Method for affinity viscosimetry and viscosimetric sensor

• US 20030054560A1
• Filed: 08/30/2002
• Published: 03/20/2003
• Est. Priority Date: 03/03/2000
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Disetronic Licensing Ag (Roche Holding AG)
• Inventors: Ehwald, Rudolf, Beyer, Uwe, Haueter, Ulrich
• Granted Patent: US 6,938,463 B2
• Time in Patent Office: Days
• US Class Current: 436/95
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: G01N 11/08 by measuring pressure required to produce a known flow
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

A method and apparatus for determining solute levels by affinity viscosimetry involving a sensitive fluid, in which the sensitive fluid flows continuously through a first hydraulic resistor in the flow direction of the dialysis chamber, and the sensitive fluid modified by dialysis simultaneously flows through another resistor, wherein the pressure differences between the resistors is determined on-line with the aid of pressure sensors and converted into a relative value which is approximately proportional to the concentration of solute.

Claims

1. A method for determining sugar levels by affinity viscosimetry involving a sensitive fluid, in which the sensitive fluid flows continuously through a first hydraulic resistor in the flow direction of the dialysis chamber, and the sensitive fluid modified by dialysis simultaneously flows through another hydraulic resistor, wherein the pressure differences between the resistors is determined on-line with the aid of pressure sensors and converted into a relative value which is approximately proportional to the concentration of sugar.

2. The method as set forth in claim 1, wherein said fluid exhibits one of a defined sugar content and no sugar content.

3. The method as set forth in claim 1, wherein said first resistor is a reference resistor and said another resistor is a measuring resistor which is approximately isothermal with said reference resistor, wherein the pressure difference which drops away across said measuring resistor and said reference resistor is determined.

4. The method as set forth in claim 3, wherein said reference resistor, said dialysis chamber and said measuring resistor are in succession on a flow path.

5. The method as set forth in claim 3, wherein said reference resistor is on one flow path and said dialysis chamber and said measuring resistor are together on a parallel flow path.

6. The method as set forth in claim 3, wherein the relative value represents the quotient between the drop in pressure at said reference resistor and the sum of the drop in pressure at said measuring resistor and a correction value leading to a linearization of the correlation with the glucose concentration.

7. A method for determining solute levels by affinity viscosimetry involving a sensitive fluid, in which the sensitive fluid flows continuously through a first resistor in the flow direction of the dialysis chamber, and the sensitive fluid modified by dialysis simultaneously flows through another resistor, wherein the pressure differences between the resistors is determined on-line with the aid of pressure sensors and converted into a relative value which is approximately proportional to the concentration of solute.

8. The method as set forth in claim 7, wherein said first resistor is a reference resistor and said another resistor is a measuring resistor which is approximately isothermal with said reference resistor, wherein the pressure difference which drops away across said measuring resistor and said reference resistor is determined.

9. The method as set forth in claim 8, wherein the relative value represents the quotient between the drop in pressure at said reference resistor and the sum of the drop in pressure at said measuring resistor and a correction value leading to a linearization of the correlation with the solute concentration.

10. A device for determining solute concentration by affinity viscosimetry involving a sensitive fluid, comprising a first resistor in the flow direction of a dialysis chamber which the sensitive fluid continuously flows through, another resistor which the sensitive fluid modified by dialysis simultaneously flows through, at least one pressure sensor which determines the pressure difference between said resistors on-line, and means for converting the pressure difference to a relative value approximately proportional to the concentration of solute.

11. A sensor for determining sugar levels by affinity viscosimetry involving a sensitive fluid, comprising a first hydraulic resistor in the flow direction of a dialysis chamber which the sensitive fluid continuously flows through, another hydraulic resistor which the sensitive fluid modified by dialysis simultaneously flows through, pressure sensors which determine the pressure differences between said resistors on-line, and a device by means of which the pressure differences are converted into a relative value which is approximately proportional to the concentration of sugar.

12. The sensor as set forth in claim 11, further comprising one of a continuously conveying pump or suction device which is coupled to a flow path with at least two pressure sensors, on which flow path said first hydraulic resistor, the dialysis chamber and the another hydraulic resistor are arranged in succession in the flow direction, wherein the flow resistors are in joint contact with one of a person'"'"'s body, a temperature-stabilized device or a heat conductor, and the expandable volume content of the flow path between said first hydraulic resistor and said another hydraulic resistor is smaller than the volume of sensitive fluid moved by the pump or suction device within 15 minutes.

13. The sensor as set forth in claim 11, further comprising two parallel flow paths coupled to one or more pump or suction devices which maintain a constant relation between the flows on the two flow paths;

said first hydraulic resistor on one flow path and said dialysis chamber and said another hydraulic resistor on the other flow path, said another hydraulic resistor downstream of the dialysis chamber;

a pressure sensor arranged on each of the two flow paths for measuring the drop in pressure across the respective flow resistors, wherein the resistors are in joint contact with one of a person'"'"'s body, a temperature-stabilized device or a heat conductor.

14. The sensor as set forth in claim 12, wherein a deformable membrane of the pressure sensors lies between the atmosphere and a suitable measuring point on the flow path, so measuring the drop in pressure across said resistors.

15. The sensor as set forth in claim 13, wherein a deformable membrane of the pressure sensors lies between suitable points on the flow paths, so measuring the drop in pressure across said resistors.

16. A device for determining sugar levels by affinity viscosimetry involving a sensitive fluid, comprising a first resistor through which the sensitive fluid flows, a dialysis chamber through which the sensitive fluid flows, another resistor through which the sensitive fluid modified by dialysis simultaneously flows, at least one pressure sensor which determines the pressure difference between said resistors on-line, and means for converting the pressure difference to a relative value approximately proportional to the sugar level.

17. The device as set forth in claim 16, further comprising one of a continuously conveying pump or suction device which is coupled to the flow path of the sensitive fluid, on which flow path first resistor, the dialysis chamber and the another resistor are arranged in succession in the flow direction.

18. The device according to claim 17, wherein the resistors are in contact with one of a person'"'"'s body, a temperature-stabilized device or a heat conductor.

19. The device according to claim 16, further comprising two parallel flow paths coupled to one or more pump or suction devices, said first resistor on one flow path and said dialysis chamber and another resistor on the other flow path, said another resistor downstream of said dialysis chamber, and a pressure sensor associated with each of the flow paths for measuring the drop in pressure across the respective resistors.

20. The device according to claim 19, wherein the resistors are in contact with one of a person'"'"'s body, a temperature-stabilized device or a heat conductor.