Techniques to improve polyurethane membranes for implantable glucose sensors

• US 9,801,574 B2
• Filed: 10/05/2015
• Issued: 10/31/2017
• Est. Priority Date: 05/22/2002
• Status: Expired due to Term

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Tapsak, Mark A., Rhodes, Rathbun K., Shults, Mark C., McClure, Jason D.
• Primary Examiner(s): JANG, CHRISTIAN YONGKYUN
• Application Number:
  US14/875,539
• Publication Number:
  US 20160022186A1
• Time in Patent Office: 757 Days
• 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. An implantable device for measuring an analyte in a biological fluid, comprising:

an implantable sensor comprising an electrochemically reactive surface; and

a membrane disposed over at least a portion of the electrochemically reactive surface, wherein the membrane comprises a matrix comprising a first polymer and a second polymer dispersed throughout the matrix, wherein the first polymer is polyurethane urea, wherein the second polymer comprises at least one hydrophilic component, wherein the hydrophilic component of the second polymer forms in the membrane hydrophilic segments along which the analyte diffuses.

2. The implantable device of claim 1, wherein the second polymer comprises polyethylene oxide.

3. The implantable device of claim 2, wherein polyethylene oxide comprises about 20% by weight of the second polymer.

4. The implantable device of claim 2, wherein the polyethylene oxide has an average molecular weight from 200 to 3,000 Daltons.

5. The implantable device of claim 1, wherein the hydrophilic segments comprise a network of microdomains.

6. The implantable device of claim 5, wherein the microdomains are not photomicroscopically observable when hydrated at 400×

magnification or less.

7. The implantable device of claim 5, wherein the network of are substantially dispersed throughout the matrix.

8. The implantable device of claim 1, wherein the membrane has a thickness from 5 to 100 microns.

9. The implantable device of claim 1, wherein the membrane is configured to yield calibration factors that are stable over the life of the sensor.

10. The implantable device of claim 1, wherein the analyte is glucose.