Ph Sensor

• US 20080294069A1
• Filed: 06/23/2005
• Published: 11/27/2008
• Est. Priority Date: 06/24/2004
• Status: Active Grant

• Current Assignee: University College Cardiff Consultants Ltd (Cardiff University)
• Original Assignee: University College Cardiff Consultants Ltd (Cardiff University)
• Inventors: Waters, Mark Geoffrey John, Stickler, David James
• Granted Patent: US 8,062,234 B2
• Time in Patent Office: Days
• US Class Current: 600/584
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/6852 Catheters

Abstract

The invention relates to a pH sensor for use in a catheter drainage system. The invention also relates to a catheter, drainage bag or connection unit comprising the pH sensor of the present invention, methods of using the pH sensor and methods of making the pH sensor.

Claims

1. A pH sensor for incorporation into a catheter drainage system wherein the pH sensor comprises a polymer matrix comprising a chemically bound pH indicator, wherein in use the pH indicator only responds to a sustained increase in pH.

2. The pH sensor according to claim 1, that can be incorporated into a catheter drainage system at any position provided that during use it is visible.

3. The pH sensor according to claim 1 or claim 2 that is formed as a disc for insertion into a drainage bag of a catheter drainage system.

4. The pH sensor according to claim 1 or claim 2, that is formed as an annular ring having a bore allowing fluid to pass through the sensor.

5. The pH sensor according to any one of claims 1 and 2, wherein the polymer matrix is polyurethane or cellulose acetate.

6. The pH sensor according to any one of claims 1 and 2, wherein the pH indicator changes colour in response to an increase in pH of a bacterial biofilm that develops on the sensor surface.

7. The pH sensor according to any one of claims 1 and 2, wherein the pH indicator changes colour in response to an increase in pH from pH 6 to pH 7.6 or above.

8. The pH sensor according to any one of claims 1 and 2, wherein the pH indicator is selected from the indicators given in Table 1.

9. The pH sensor according to any one of claims 1 and 2, wherein the pH indicator is neutral red, bromothymol blue, cresol red, phenol red, 3-(m-) flurescein and rosolic acid.

10. The pH sensor according to any one of claims 1 and 2, wherein in use the pH indicator responds to an increase in pH, when the increased pH level is maintained for more than 6 hours.

11. The pH sensor according to any one of claims 1 and 2, wherein in use the pH indicator responds to an increase in pH, when the increased pH level is maintained for more than 9 hours.

12. The pH sensor according to any one of claims 1 and 2, wherein in use the pH indicator responds to an increase in pH, when the increased pH level is maintained for more than 12 hours.

13. The pH sensor according to claim 1, which additionally comprises a matrix stabiliser.

14. The pH sensor according to claim 13, wherein the matrix'"'"' stabiliser is Scotchlite or a quaternary ammonium compound.

15. The pH sensor according to claim 1, wherein the polymer matrix is cellulose acetate and the pH indicator is bromothymol blue.

16. The pH sensor according to any one of claims 1 and 2, which is provided with a reference material to assist in determining when the pH indicator has responded to a sustained increase in pH.

17. A catheter comprising a pH sensor according to any one of claims 1 and 2.

18. A drainage bag comprising a pH sensor according to any one of claims 1, 2, 13, 14, or 15.

19. The catheter according to claim 16, wherein the pH sensor is positioned at the end of the catheter that in use is connected to a drainage unit.

20. A drainage unit comprising a pH sensor according to any one of claims 1, 2, 13, 14, or 15.

21. The drainage unit according to claim 18, wherein the drainage unit comprises a drainage bag and drainage bag tubing, and the pH sensor is positioned at the end of the drainage bag tubing that in use is connected to the catheter.

22. A connection unit comprising the pH sensor according to any one of claims 1, 2, 13, 14, or 15, wherein the connection unit can be inserted between the drainage unit and the catheter.

23. Use of the pH sensor according to any one of claims 1, 2, 13, 14, or 15 for predicting impending catheter encrustation and blockage comprising positioning the pH sensor in the flow of urine from a catheter and monitoring for a change in the pH sensor indicting a sustained increase in pH.

24. A method of making a pH sensor according to any one of claims 1, 2, 13, 14, or 15, comprising covalently linking the pH indicator to the polymer matrix and then curing the derived composition to form the pH sensor.

25. The method of claim 22, wherein the polymer matrix comprises polyethylene glycol.