MEMS Functional Element Surface Structuring for Liquid Residue Control

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Solution Overview

Problem

MEMS devices with deflectable functional elements in fluidic connection with the environment suffer from surface contamination after exposure to liquids, leading to deterioration of operational characteristics due to liquid residuals and contaminants during the drying process.

Innovation Solution

Implementing a surface structure with a liquid contact angle gradient or difference, where certain subsections have higher wettability than others, directing liquid and contaminants to specific regions during drying to minimize contamination impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the functional element is exposed to liquid for environmental sensing, then the device can detect environmental parameters, but surface contamination with liquid residuals deteriorates operational characteristics

Engineering Contradiction:

Improveenvironmental sensing capabilityVSAvoidoperational characteristic

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The functional element surface is divided into multiple subsections with different wettability characteristics. The first subsection has higher liquid wettability to attract and retain liquid, while the second subsection has lower wettability to repel liquid and prevent contamination. This segmentation allows the surface to simultaneously enable environmental sensing while protecting critical areas from liquid residual contamination.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the functional element surface are assigned different local properties regarding liquid interaction. The first subsection is designed with hydrophilic characteristics (higher wettability) to facilitate liquid contact for sensing, while the second subsection is designed with hydrophobic characteristics (lower wettability) to minimize contamination. This local quality differentiation resolves the contradiction by allowing beneficial liquid contact in specific areas while preventing harmful contamination in others.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If a uniform surface coating is applied to the functional element, then manufacturing is simplified, but liquid residuals contaminate the entire surface causing operational deterioration

Engineering Contradiction:

Improvesurface coating processVSAvoidsurface contamination

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

Instead of a uniform surface coating, the invention applies different surface treatments to different subsections of the functional element. The first subsection receives a coating or treatment that increases liquid wettability, while the second subsection receives a coating or treatment that decreases liquid wettability. This approach increases manufacturing complexity slightly but effectively prevents widespread contamination by directing liquid residuals to specific tolerant areas.

Inventive Principle:

Principle #3Local quality

3Reliability

If external barriers are added to prevent liquid contact, then surface contamination is reduced, but device complexity and cost increase

Engineering Contradiction:

Improveprotection from contaminationVSAvoidbarrier structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The functional element surface itself provides the protection mechanism through its differentiated wettability properties. The second subsection with lower wettability acts as a self-protecting region that naturally repels liquid and prevents contamination without requiring external barriers. This self-service approach maintains reliability while avoiding the complexity and cost of additional protective structures.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention uses thin surface coatings or monolayers applied directly to the functional element surface to create different wettability regions. These thin films provide the necessary protective function without adding significant structural complexity or bulk to the device design.

Inventive Principle:

Principle #30Flexible shells and thin films

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

Enhances environmental robustness of MEMS devices, reducing the need for external barriers and lowering module costs while maintaining operational characteristics.

Implementation Method 1

the first subsection of the overall surface area has a first surface structure with a higher liquid wettability

Methodology Applied

Scientific EffectWetting: Wetting

Implementation Method 2

a second surface structure of the second subsection of the overall surface area with a lower liquid wettability than the first surface structure

Methodology Applied

Scientific EffectHydrophobicity: Hydrophobe

Data Source

PatentUS20250373966A1MEMS device and method for fabricating a MEMS device

Publication Date: 2025.12.04 INFINEON TECHNOLOGIES AG

AI summary

In an embodiment, a MEMS device includes a functional element in a fluidic connection with an environment, wherein the functional element comprises an overall surface area with at least a first subsection and an adjacent second subsection, wherein the functional element is in the first subsection of the overall surface area less prone to a surface contamination than in the second subsection of the overall surface area, and wherein the first subsection of the overall surface area has a first surface structure with a higher liquid wettability than a second surface structure of the second subsection of the overall surface area.