Amorphous Gas Sensor Cap Layer Oxidation Prevention

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Solution Overview

Problem

Conventional gas sensors, particularly hydrogen gas sensors using micro-electromechanical systems (MEMS), face performance inadequacies due to oxidation of sensitive layer elements, leading to destruction of the amorphous structure and promotion of crystallization, which hampers desired gas absorption characteristics.

Innovation Solution

A gas sensor design incorporating a cap layer on the sensitive layer to prevent oxidation, using an amorphous material like PdCuSi with a catalytic element and a cap layer containing elements that prevent oxidation, such as palladium or silicon, to maintain the amorphous structure and enhance gas absorption capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional gas sensor structure is used, then the device is simple, but the sensitive layer oxidizes leading to destruction of amorphous structure and poor gas absorption characteristics

Engineering Contradiction:

Improvegas absorption characteristicsVSAvoidsensor structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A cap layer is introduced as an intermediary protective element between the sensitive layer and the external environment. This cap layer prevents oxidation of the sensitive layer while allowing the sensor to maintain its gas absorption functionality, thus resolving the contradiction between reliability and structural simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sensor structure is transformed into a composite multi-layer system consisting of the sensitive layer, cap layer, and optional buffer layer. This composite structure provides both protection against oxidation and maintenance of gas absorption characteristics, overcoming the limitations of conventional single-layer designs.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If the sensitive layer is exposed to air, then the structure remains simple, but oxidation occurs destroying the amorphous structure

Engineering Contradiction:

Improveamorphous structureVSAvoidlayer structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The cap layer serves as a protective intermediary that isolates the sensitive layer from oxygen in the air, preventing oxidation and preserving the amorphous structure. This simple protective layer effectively solves the stability issue without requiring complex structural modifications.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cap layer creates an inert protective environment around the sensitive layer, shielding it from oxidative conditions in the external air. This effectively maintains the amorphous structure by preventing harmful chemical reactions while adding minimal structural complexity.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

3Reliability

If no cap layer is provided, then the manufacturing process is simple, but gas absorption characteristics deteriorate due to oxidation

Engineering Contradiction:

Improvegas absorption characteristicsVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The cap layer is introduced as a protective intermediary during manufacturing and operation, preventing oxidation of the sensitive layer. This simple additive layer significantly improves gas absorption characteristics without substantially complicating the manufacturing process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cap layer is formed in advance during the manufacturing process to provide pre-protection against oxidation. This preliminary protective action ensures that the sensitive layer maintains its gas absorption characteristics throughout the device lifecycle, with minimal impact on manufacturing simplicity.

Inventive Principle:

Principle #10Preliminary action

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 cap layer effectively prevents oxidation, maintaining the amorphous structure and improving gas absorption and release characteristics, resulting in enhanced reliability and performance of the gas sensor.

Implementation Method 1

a film structure which covers the fixed electrode, forms a cavity inside the film structure, and includes: a sensitive layer formed of an amorphous material containing a metal element

Methodology Applied

Scientific EffectGas absorption: Absorption (physical)

Implementation Method 2

A gas sensor design incorporating a cap layer on the sensitive layer to prevent oxidation

Methodology Applied

Scientific EffectOxidation prevention: Oxidation

Data Source

PatentUS11796502B2Gas sensor

Publication Date: 2023.10.24 KK TOSHIBA

AI summary

According to one embodiment, a gas sensor includes a fixed electrode, and a film structure which covers the fixed electrode, forms a cavity inside the film structure, and includes a sensitive layer formed of an amorphous material containing a metal element, and a cap layer provided on the sensitive layer. The film structure is allowed to be deformed when the sensitive layer absorbs a predetermined gas.