Compact Gas Sensor With MEMS Capillary Diffusion

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Solution Overview

Problem

Conventional gas sensors are not compact enough to fit into small spaces and may not be durable or stable, limiting their application in various settings where small size and reliability are crucial.

Innovation Solution

A compact gas sensor design featuring a housing with a central stepped cavity, MEMS elements with apertures for gas diffusion, and a chemically based stack of material including diffusion electrodes and electrolyte gel, allowing for efficient gas sensing and electrical current generation without the need for glues or adhesives, and enabling surface-mount board assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional gas sensor design is used, then gas sensing function is provided, but the sensor size is too large to fit into small spaces

Engineering Contradiction:

Improvesensor sizeVSAvoiddurability and stability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent employs a stacked configuration where multiple functional layers (diffusion electrode layer, electrolyte gel layer, MEMS element layer) are nested within each other in a compact vertical arrangement. The MEMS element is positioned within a cavity in the housing, and layers are stacked to minimize horizontal footprint while maintaining all necessary components for gas sensing operation.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent utilizes a porous diffusion electrode layer that allows gas molecules to diffuse through its structure to reach the electrolyte and electrode interface. This porous structure enables efficient gas transport in a compact design, maintaining sensing effectiveness while reducing overall sensor volume.

Inventive Principle:

Principle #31Porous materials

2Device complexity

If conventional gas sensor design is used, then gas sensing is provided, but the sensor structure is complex requiring glues or adhesives

Engineering Contradiction:

Improvestructural complexityVSAvoidassembly process

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The patent merges multiple functional components into an integrated stacked structure where the diffusion electrode layer, electrolyte gel layer, and MEMS element layer are positioned in direct contact with each other. This integration eliminates the need for separate adhesives or glues to bond components, as the layers are designed to interface directly, simplifying the manufacturing process.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If conventional gas sensor design is used, then gas detection is provided, but the sensor cannot withstand reflow temperatures for board assembly

Engineering Contradiction:

Improvecompatibility with board assemblyVSAvoidreflow temperature resistance

Core Design Contradiction:

Adaptability or versatilityVSTemperature

Solution Approach 1:

The patent employs high temperature material in the sensor receptacle that can withstand reflow temperatures during board assembly. This material parameter change allows the sensor to survive the high-temperature soldering process without degradation, enabling direct surface-mount board assembly without requiring protective measures during reflow operations.

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

The compact gas sensor provides durable and stable operation with extended life, better fits small applications, and maintains reliability across varying temperatures, ensuring effective gas detection in confined spaces.

Implementation Method 1

The MEMS element further includes an array of apertures, placed to pass gases from ambient air to the top diffusion layer

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

Gas may diffuse into the sensor, through the back of the porous membrane to the working electrode where it is oxidized or reduced. This electrochemical reaction results in an electric current

Methodology Applied

Scientific EffectElectrochemical reaction: Electrolysis

Data Source

PatentUS11268928B2Compact gas sensor including a MEMS element having capillaries to facilitate gas diffusion

Publication Date: 2022.03.08 HONEYWELL INTERNATIONAL INC

AI summary

Apparatus and associated methods relate to a compact gas sensor (CGS) including a housing with a central stepped cavity with one or more first lead contact(s) forming a portion of a base plane in a bottom of the cavity and one or more second lead contact(s) forming a portion of a stepped plane higher than the base plane, the cavity sized to receive a chemically based stack of material made up of a bottom diffusion electrode layer, a middle electrolyte gel layer, and a top diffusion electrode layer. The bottom diffusion electrode layer is in electrical contact with the first lead contact(s). The top diffusion electrode layer electrically couples to the second lead contact(s) via an overlaying micro electromechanical system (MEMS) element layer with conductive coating. In an illustrative example, the CGS may provide gas sensing in small spaces.