Critical point drying of hydrogels in analyte sensors

Patent metadata

Field	Value
Publication number	US-9963556-B2
Application number	US-201414489728-A
Country	US
Kind code	B2
Filing date	Sep 18, 2014
Priority date	Sep 18, 2013
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

A hydrogel is dried by a critical point drying technique. The hydrogel may include indicator molecules embedded therein and may be part of a hydrogel-based device, such as, for example, an analyte sensor.

First claim

The invention claimed is:

1. A method of preparing a hydrogel for a hydrogel-based analyte sensor configured for sensing the presence of an analyte in contact with the analyte sensor, the method comprising:
applying the hydrogel to all or part of a surface of a sensor housing of the analyte sensor, wherein the hydrogel comprises indicator molecules that are configured to emit a detectable signal or a change in a detectable signal indicating the presence of the analyte;
applying a protective catalyst to the hydrogel, wherein applying the protective catalyst to the hydrogel comprises sputtering the protective catalyst on the hydrogel; and
drying the hydrogel, which (i) comprises the indicator molecules, (ii) has been applied to all or part of the surface of the sensor housing, and (iii) to which the protective catalyst has been applied, by a critical point drying technique that comprises:
replacing water within the hydrogel with an intermediate fluid that is miscible with water and CO 2 ;
replacing the intermediate fluid within the hydrogel with CO 2 ;
manipulating temperature and pressure to achieve super critical CO 2 ; and
removing the supercritical CO 2 from the hydrogel.

2. The method of claim 1 , wherein the temperature for achieving super critical CO 2 is about 30-35° C., and the pressure for achieving supercritical CO 2 is about 1000-1200 psi.

3. The method of claim 1 , further comprising storing the hydrogel-based analyte sensor at room temperature after the critical point drying step.

4. The method of claim 1 , further comprising implanting the critical point dried hydrogel-based analyte sensor into a living being without pre-hydrating the hydrogel-based analyte sensor prior to implanting.

5. The method of claim 1 , wherein the protective catalyst is platinum.

Assignees

• Senseonics Inc

Inventors

• Huffstetler Philip
• Modzelewska Aneta

Classifications

• F26B21/40

  using gases other than air · CPC title

• C08J3/00 Primary

  Processes of treating or compounding macromolecular substances · CPC title

• A61B5/1455

  using optical sensors, e.g. spectral photometrical oximeters · CPC title

• G01N21/6428

  Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" (in vivo A61B5/00; immunoassay G01N33/53) · CPC title

• A61B5/1459

  invasive, e.g. introduced into the body by a catheter · CPC title