Sensor Cavity Polymerization for Smooth Non-Thrombogenic Surfaces

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Solution Overview

Problem

There is a need for methods to create analyte sensors with immobilized functional chemistries in a polymeric matrix within a cavity, where the outer surface remains smooth and non-thrombogenic, while maintaining the functionality of the chemistries.

Innovation Solution

The method involves vacuum filling a sensor with a monomer solution containing a crosslinker and initiator, followed by polymerization, and then coating with wax to prevent water loss and oxygen ingress, with subsequent removal of the wax using an organic solvent like hexane and ultrasonic energy to achieve a smooth outer surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the cavity is filled with monomer solution and polymerized to immobilize functional chemistries, then the functional chemistry immobilization is achieved, but the outer surface becomes rough and thrombogenic

Engineering Contradiction:
Improvefunctionality of chemistriesVSAvoidthrombogenicity of surface
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A smooth outer coating is applied to the cavity before polymerization of the monomer solution. This preliminary coating protects the outer surface from becoming rough during the polymerization process, preventing thrombogenicity while allowing the polymerization to proceed inside the cavity to immobilize functional chemistries.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The smooth outer coating is selectively removed after polymerization is complete. This extraction leaves only the desired smooth outer surface of the sensor while removing the temporary protective layer, achieving both a smooth non-thrombogenic surface and proper immobilization of functional chemistries within the cavity.

Inventive Principle:
Principle #2Taking out (Extraction)

2Manufacturing precision

If the outer surface is smoothed by coating and then removing the coating, then the surface smoothness is improved, but the process complexity increases

Engineering Contradiction:
Improvesurface smoothnessVSAvoidprocess steps
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The coating material is selected to have specific properties: it forms a smooth surface when applied, can withstand the polymerization conditions, and can be selectively removed after polymerization. By changing the parameters of the coating material (selecting appropriate wax or polymer), the process achieves surface smoothness without requiring excessively complex removal procedures.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively immobilizes the analyte indicator system within the sensor, ensuring the outer surface remains smooth and non-thrombogenic, while maintaining the functionality of the chemistries, thereby enhancing the sensor's performance and biocompatibility.

Implementation Method 1

vacuum filling a sensor with a monomer solution containing a crosslinker and initiator, followed by polymerization

Methodology Applied
Scientific EffectPolymerization:

Implementation Method 2

removal of the wax using an organic solvent like hexane

Methodology Applied
Scientific EffectDissolution: Solvation

Implementation Method 3

removal of the wax using an organic solvent like hexane and ultrasonic energy

Methodology Applied
Scientific EffectUltrasonic cavitation: Ultrasonic Vibration

Data Source

PatentEP2122334B1Method for polymerizing a monomer solution within a cavity to generate a smooth polymer surface
Publication Date: 2018.01.24 MEDTRONIC MINIMED INC
  • EP2122334B1 patent drawingFigure 1~2
  • EP2122334B1 patent drawingFigure 3A~3B
  • EP2122334B1 patent drawingFigure 4

AI summary

IThe present invention relates to methods for polymerizing a monomer solution (15) comprising a polymerization initiator and an analyte indicator within a cavity (6) in an optical fiber covered by a porous membrane (14) to generate a smooth polymer surface. More specifically, the method can be used to provide a medical device or sensor (2) with a smooth polymer surface.