Techniques to improve polyurethane membranes for implantable glucose sensors

• US 8,053,018 B2
• Filed: 01/15/2010
• Issued: 11/08/2011
• Est. Priority Date: 05/22/2002
• Status: Expired due to Term

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: McClure, Jason D., Shults, Mark C., Tapsak, Mark A., Rhodes, Rathbun K.
• Primary Examiner(s): Yuan; Dah-Wei
• Assistant Examiner(s): BOWMAN, ANDREW J
• Application Number:
  US12/688,737
• Publication Number:
  US 20100119693A1
• Time in Patent Office: 662 Days
• Field of Search: 435/25, 204/403, 427/2.11, 427/2.12, 427/430.1, 427/443.2
• US Class Current: 427/2.11
• 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 69/1411 containing dispersed material in a continuous matrix
• 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 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 and the second polymer are not same polymers wherein the second polymer is a hydrophobic-hydrophilic co-polymer comprising a hydrophobic segment and a hydrophilic segment, 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 with the second polymer;

applying the solution to the sensor;

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 comprises a polyurethane segment.

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

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

6. The method of claim 5, wherein the membrane has an oxygen-to-glucose permeability ratio of approximately 200:

1.

7. 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.

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

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

providing a sensor 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 and the second polymer are not same polymers, 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.

10. The method of claim 9, further comprising:

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

11. The method of claim 10, wherein maintaining the solution at a temperature comprises heating the solution to a temperature of at least about 70°

C.

12. The method of claim 10, further comprising:

forming a film from the solution at the temperature; and

drying the film to form a membrane.

13. The method of claim 12, wherein the membrane has a thickness of from about 5 microns to about 100 microns.

14. The method of claim 9, 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.

15. The method of claim 9, wherein the analyte is glucose.

16. The method of claim 15, wherein the membrane has an oxygen-to-glucose permeability ratio of approximately 200:

1.

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

26. The method of claim 9, wherein the first polymer is a hydrophobic-hydrophilic polymer comprising a hydrophobic segment and a hydrophilic segment, and wherein the first polymer has a ratio of an amount of hydrophobic content to hydrophilic content different than a ratio of an amount of hydrophobic content to hydrophilic content of the second polymer.

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

providing a sensor 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 and the second polymer are not same polymers wherein the second polymer is a hydrophobic-hydrophilic co-polymer comprising a hydrophobic segment and a hydrophilic segment, 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 with the second polymer;

applying the solution to the sensor;

forming a film from the solution at the temperature; and

drying the film to form the membrane.

19. The method of claim 18, 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.

20. The method of claim 18, wherein the second polymer comprises a polyurethane segment.

21. The method of claim 18, wherein the membrane has a thickness of from about 5 microns to about 100 microns.

22. The method of claim 18, wherein the analyte is glucose.

23. The method of claim 22, wherein the membrane has an oxygen-to-glucose permeability ratio of approximately 200:

1.

24. The method of claim 18, wherein maintaining the solution at a temperature comprises heating the solution to a temperature of at least about 70°

C.

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