Hermetic Seal for Optical Elements Using Fluoropolymer Interference Fit

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Solution Overview

Problem

Existing methods for sealing optical elements within metal housings for autoclave sterilization are costly, labor-intensive, and have short life cycles, leading to potential moisture intrusion and image distortion.

Innovation Solution

A hermetic seal is achieved using a fluoropolymer dispersed along the interior edge of a metal mount or optical element, which is heated to create an interference fit and provide a durable, moisture-tight barrier when cooled, allowing for easy assembly and high reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional methods such as braising, fritting, O-rings, adhesive, or brazing are used to seal optical elements, then hermetic sealing is achieved, but the assembly process becomes costly, labor-intensive, and has a short life cycle

Engineering Contradiction:

Improvehermetic sealing reliabilityVSAvoidassembly cost and complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the physical state of the sealing material from solid (adhesive, O-ring) to liquid (molten low-melting-point metal) during assembly, then to solid upon cooling. This phase change enables simple dip-coating assembly while achieving hermetic seals that withstand autoclave sterilization, resolving the contradiction between sealing reliability and manufacturing simplicity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces complex mechanical sealing systems (O-rings, adhesives, brazing procedures) with a thermal-based sealing mechanism using low-melting-point metal alloys. The sealing material is applied as a liquid coating, heated to melt and flow into crevices, then cooled to form a permanent hermetic bond, eliminating labor-intensive assembly while maintaining seal integrity under sterilization

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If optical elements are subjected to autoclave sterilization, then effective pathogen elimination is achieved, but moisture penetration through hermetic seals causes condensation and image distortion

Engineering Contradiction:

Improvesterilization effectivenessVSAvoidmoisture intrusion and condensation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses composite sealing structures combining low-melting-point metal alloys with complementary materials to create hermetic seals that are both sterilization-resistant and moisture-impermeable. The composite approach ensures seals maintain integrity under high-temperature autoclave conditions while preventing moisture penetration that would cause condensation on optical surfaces

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies multiple layers of sealing material and designs overlapping seal zones before autoclave sterilization to create redundant barriers against moisture intrusion. This pre-established multi-layer protection cushions against the harmful effects of sterilization-induced moisture, preventing condensation even if one seal layer is compromised

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Duration of action of stationary object

If hermetic seals are made more robust to prevent moisture penetration, then seal durability improves, but assembly complexity and cost increase

Engineering Contradiction:

Improveseal life cycleVSAvoidsealing mechanism complexity

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent employs self-service sealing where the low-melting-point metal alloy automatically flows and conforms to the mating surface geometry when heated, creating adaptive hermetic seals without requiring precision pre-machining or complex alignment fixtures. The material self-adjusts to fill gaps and crevices, achieving durable seals through simple dip-coating assembly while extending service life through autoclave-compatible materials

Inventive Principle:

Principle #25Self-service

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

The method offers a cost-effective, durable, and reliable seal that withstands multiple autoclave cycles, reducing moisture penetration and extending the service life of optical elements in medical devices.

Implementation Method 1

The metal mount and fluoropolymer are then heated to a temperature exceeding the melting point of the fluoropolymer

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

Once heated the optical element is pressed into the metal mount and allowed to cool

Methodology Applied

Scientific EffectCooling and solidification: Freezing

Data Source

PatentUS11320648B2Hermetic seal and a method of assembling

Publication Date: 2022.05.03 ACCESS OPTICS INC

AI summary

A hermetic seal between an optical element and a metal mount or housing using a fluoropolymer. The fluoropolymer is dispersed along the interior edge of the metal mount. The metal mount and fluoropolymer are then heated to a temperature exceeding the melting point of the fluoropolymer. Once heated the optical element is pressed into the metal mount and allowed to cool. The metal mount, optical element and thickness of fluoropolymer are sized to provide an interference fit between the metal mount and optical element.