QCM Sensor Gasket Seal for Contamination Prevention

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Solution Overview

Problem

Existing quartz crystal microbalance (QCM) sensors lack adequate sealing, allowing deposition materials and contaminants to ingress and cause electrical shorts or discontinuities, and are challenging to manufacture due to the fragility of the quartz crystal.

Innovation Solution

A QCM sensor design featuring a gasket seal integrally formed around the quartz crystal substrate, using perfluoroelastomer materials for chemical resistance and vibration isolation, with an overmolded or interference fit configuration to prevent contamination and minimize force on the crystal, combined with a chemically resistant protective coating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional sensor body design is used without an integrated seal, then the manufacturing process is simpler, but deposition materials and contaminants can ingress into the sensor body causing electrical shorts or discontinuities

Engineering Contradiction:

Improveprevention of electrical shortVSAvoidsensor body structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The seal is integrated directly into the quartz crystal substrate, merging the sealing function with the oscillating component itself. This eliminates the need for separate seal components and complex assembly, while providing comprehensive sealing around the crystal periphery to prevent contaminant ingress and electrical shorts

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If tight tolerances are used between the quartz crystal plate and sensor housing components to prevent deposit ingress, then sealing effectiveness is improved, but manufacturing cost increases and the quartz crystal is more prone to fracture

Engineering Contradiction:

Improvesealing effectivenessVSAvoidmanufacturing cost and crystal fragility

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The seal is segmented into two distinct portions: a first seal portion extending from the front surface of the crystal and a second seal portion extending from the rear surface. This segmentation allows each portion to be optimized independently and work together to provide comprehensive sealing without requiring tight tolerances across the entire assembly

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The seal acts as an intermediary element between the quartz crystal plate and the sensor housing, providing a compliant sealing interface that accommodates tolerance variations while preventing contaminant ingress. The seal material bridges the gap between rigid components, allowing for easier manufacturing

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If an O-ring is compressed onto the quartz crystal plate to prevent chemical ingress, then sealing is improved, but the thin and brittle crystal plate is difficult to handle and may fracture

Engineering Contradiction:

Improveprevention of chemical ingressVSAvoidhandling difficulty

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The seal is merged with the quartz crystal substrate to form an integrated crystal seal component. This eliminates the need to handle and install separate O-rings on the fragile crystal plate, as the seal is already attached to the crystal during manufacturing, simplifying subsequent handling and assembly operations

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If the seal extends from both front and rear surfaces of the crystal substrate, then comprehensive sealing is achieved, but the device complexity increases

Engineering Contradiction:

Improvecomprehensive sealingVSAvoidseal configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The seal is divided into two segments (front and rear portions) that extend from opposite surfaces of the crystal. This segmentation provides comprehensive sealing coverage while maintaining a simple overall structure that is easy to manufacture and install

Inventive Principle:

Principle #1Segmentation

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 solution provides a robust, sealed environment that prevents contamination and reduces the risk of electrical failures, simplifies manufacturing, and enhances signal-to-noise ratio by minimizing vibration-induced frequency shifts.

Implementation Method 1

a gasket seal disposed about the periphery of the crystal substrate configured to prevent ingress of fluids into the sensor housing

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

the perfluoroelastomer material is selected to be chemically resistant to corrosive elements present in the process environment

Methodology Applied

Scientific EffectChemical resistance:

Implementation Method 3

gasket seal is wrapped around and isolates the crystal component from external vibration sources in the process environment

Methodology Applied

Scientific EffectVibration isolation: Damping

Data Source

PatentUS20240402128A1QCM sensor

Publication Date: 2024.12.05 INFICON INC

AI summary

A quartz crystal microbalance (QCM) sensor, comprises a sensor housing and a crystal component supported within the sensor housing. The crystal component includes a quartz crystal substrate and a gasket seal disposed about the periphery of the quartz crystal substrate configured to prevent ingress of fluids into the sensor housing.