TECHNIQUES TO IMPROVE POLYURETHANE MEMBRANES FOR IMPLANTABLE GLUCOSE SENSORS

• US 20130030273A1
• Filed: 09/28/2012
• Published: 01/31/2013
• 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 8,865,249 B2
• Time in Patent Office: Days
• US Class Current: 600/365
• 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 preparing an implantable homogeneous membrane, the method comprising:

forming a composition comprising a dispersion of a hydrophobic-hydrophilic copolymer within a matrix of a hydrophobic polymer;

maintaining the composition at a temperature sufficient to maintain solubility of the hydrophobic-hydrophilic copolymer and the hydrophobic polymer;

applying the composition at the temperature to at least one of a substrate or a layer on the substrate to form a film thereon; and

drying the film to form a membrane.

2. The method of claim 1, wherein forming a composition comprises forming a mixture or a blend.

3. The method of claim 1, wherein maintaining the composition at the temperature comprises heating the composition at a temperature of about 70°

C.

4. The method of claim 1, wherein the drying the film comprises drying at a temperature of from about 120°

C. to about 150°

C.

5. The method of claim 1, wherein the hydrophobic-hydrophilic copolymer comprises a hydrophilic component comprising polyethylene oxide.

6. The method of claim 1, wherein the hydrophobic polymer comprises polyurethane.

7. The method of claim 1, wherein the membrane has an oxygen-to-glucose permeability ratio of approximately 200:

1.

8. The method of claim 1, wherein the substrate comprises an electrode of a continuous analyte sensor.

9. The method of claim 8, wherein the continuous analyte sensor is a continuous glucose sensor.

10. The method of claim 1, wherein the membrane is configured to change a ratio of oxygen to glucose from a concentration ratio in a body fluid to a new ratio in which there is a stoichiometric excess of oxygen in the enzyme layer.

11. The method of claim 1, wherein the layer is an enzyme layer.

12. The method of claim 11, further comprising applying an enzyme on the substrate to form an enzyme layer thereon.

13. A continuous analyte sensor for measuring a glucose concentration in a host, the continuous analyte sensor comprising:

a membrane configured to regulate transport of analytes, the membrane comprising;

a first domain comprising a hydrophobic-hydrophilic copolymer within a matrix of a hydrophobic polymer; and

a second domain comprising an enzyme.

14. The continuous analyte sensor of claim 13, wherein the hydrophobic polymer comprises polyurethane.

15. The continuous analyte sensor of claim 13, wherein the membrane has an oxygen-to-glucose permeability ratio of approximately 200:

1.

16. The continuous analyte sensor of claim 13, wherein the membrane is configured to change a ratio of oxygen to glucose from a concentration ratio in a body fluid to a new ratio in which there is a stoichiometric excess of oxygen in the second domain.