TECHNIQUES TO IMPROVE POLYURETHANE MEMBRANES FOR IMPLANTABLE GLUCOSE SENSORS

• US 20100119693A1
• Filed: 01/15/2010
• Published: 05/13/2010
• Est. Priority Date: 05/22/2002
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Shults, Mark C., Tapsak, Mark A., Rhodes, Rathbun K., McClure, Jason D.
• GRANTED PATENT: US 8,053,018 B2
• Time in patent office: 0 Days
• US Class Current: 427/2.120
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 2562/125 characterised by the manufacture of electrodes
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61L 31/12 Composite materials, i.e. containing one material dispersed in a matrix of the same or different material
• CPC Class Codes: B01D 69/141 Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
• CPC Class Codes: B01D 71/54 Polyureas; Polyurethanes
• CPC Class Codes: B01D 71/80 Block polymers
• CPC Class Codes: B05D 3/007 After-treatment
• CPC Class Codes: B05D 5/00 Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
• CPC Class Codes: C12Q 1/002 Electrode membranes
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: Y10T 428/31551 Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]

Abstract

The invention provides an implantable membrane for regulating the transport of analytes therethrough that includes a matrix including a first polymer; and a second polymer dispersed throughout the matrix, wherein the second polymer forms a network of microdomains which when hydrated are not observable using photomicroscopy at 400× magnification or less. In one aspect, the homogeneous membrane of the present invention has hydrophilic domains dispersed substantially throughout a hydrophobic matrix to provide an optimum balance between oxygen and glucose transport to an electrochemical glucose sensor.

Claims

1. A method for fabricating a device for measuring a concentration of an analyte, the method comprising:

providing a sensor mechanism configured to measure an analyte or a product of a reaction associated with the analyte;

forming a solution comprising a blend of a first polymer and a second polymer, wherein a segment of the first polymer and a segment of the second polymer are both formed of a same monomer unit;

maintaining the solution at a temperature sufficient to maintain solubility of the first polymer and the second polymer;

applying the solution to the sensor mechanism;

forming a film from the solution at the temperature; and

drying the film to form a membrane.

2. The method of claim 1, wherein the monomer unit is selected from the group consisting of a polyurethane, a vinyl polymer, a polyether, a polyester, a polyamide, a polysiloxane, and a polycarbosiloxane.

3. The method of claim 1, wherein the second polymer is a hydrophobic-hydrophilic co-polymer comprising a hydrophobic segment and a hydrophilic segment.

4. The method of claim 1, wherein the second polymer comprises a polyurethane segment.

5. The method of claim 1, wherein the membrane has a thickness of from about 5 microns to about 100 microns.

6. The method of claim 1, wherein the analyte is glucose.

7. The method of claim 6, wherein the membrane has an oxygen-to-glucose permeability ratio of approximately 200:

1.

8. The method of claim 1, wherein maintaining the solution at a temperature comprises heating the solution to a temperature of at least about 70°

C.

9. The method of claim 1, wherein the first polymer is a homopolymer.

10. A method for fabricating a device for measuring a concentration of an analyte, the method comprising:

providing a sensor mechanism configured to measure an analyte or a product of a reaction associated with the analyte;

forming a solution comprising a blend of a first polymer and a second polymer, wherein the first polymer is a hydrophilic polymer comprising a hydrophilic segment, wherein the second polymer is a hydrophobic-hydrophilic co-polymer comprising a hydrophobic segment and a hydrophilic segment, and wherein the hydrophilic segment of the first polymer and the hydrophilic segment of the second polymer are both formed of a same block; and

applying the solution to the sensor mechanism.

11. The method of claim 10, further comprising:

maintaining the solution at a temperature sufficient to maintain solubility of the first polymer and the second polymer.

12. The method of claim 11, wherein maintaining the solution at a temperature comprises heating the solution to a temperature of at least about 70°

C.

13. The method of claim 11, further comprising:

forming a film from the solution at the temperature; and

drying the film to form a membrane.

14. The method of claim 13, wherein the membrane has a thickness of from about 5 microns to about 100 microns.

15. The method of claim 10, wherein the second polymer comprises at least one block selected from the group consisting of a polyurethane, a vinyl polymer, a polyether, a polyester, a polyamide, a polysiloxane, a polycarbosiloxane, a polyethylene oxide, and copolymers thereof.

16. The method of claim 10, wherein the analyte is glucose.

17. The method of claim 16, wherein the membrane has an oxygen-to-glucose permeability ratio of approximately 200:

1.

18. The method of claim 10, wherein the first polymer is a homopolymer.

19. A method for fabricating a device for measuring a concentration of an analyte, the method comprising:

providing a sensor mechanism configured to measure an analyte or a product of a reaction associated with the analyte;

forming a solution comprising a matrix comprising a first polymer, wherein the solution further comprises a second polymer dispersed throughout the matrix, wherein the first polymer forms a network of hydrophilic microdomains throughout the matrix to create a pathway for analyte diffusion across a membrane, and wherein a segment of the first polymer and a segment of the second polymer are both formed of a same monomer unit;

maintaining the solution at a temperature sufficient to maintain solubility of the first polymer and the second polymer;

applying the solution to the sensor mechanism;

forming a film from the solution at the temperature; and

drying the film to form the membrane.

20. The method of claim 19, wherein the monomer unit is selected from the group consisting of a polyurethane, a vinyl polymer, a polyether, a polyester, a polyamide, a polysiloxane, and a polycarbosiloxane.

21. The method of claim 19, wherein the second polymer is a hydrophobic-hydrophilic co-polymer comprising a hydrophobic segment and a hydrophilic segment.

22. The method of claim 19, wherein the second polymer comprises a polyurethane segment.

23. The method of claim 19, wherein the membrane has a thickness of from about 5 microns to about 100 microns.

24. The method of claim 19, wherein the analyte is glucose.

25. The method of claim 24, wherein the membrane has an oxygen-to-glucose permeability ratio of approximately 200:

1.

26. The method of claim 19, wherein maintaining the solution at a temperature comprises heating the solution to a temperature of at least about 70°

C.

27. The method of claim 19, wherein the first polymer is a homopolymer.