Sensor Element Recess for Mechanical Stress Isolation

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Solution Overview

Problem

Existing sensor elements and assemblies are sensitive to external stresses, which cause errors and variations in measurement signals due to the transmission of forces and stresses to the sensitive sensor portions during production and curing.

Innovation Solution

A sensor element with a recess on the periphery of the substrate layer's upper side, which mechanically isolates the sensitive sensor portion, and a sensor assembly with a recess around the opening, decoupling it from external forces, using a combination of substrate layers and bridge parts to prevent stress transmission and enhance mechanical isolation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the sensitive sensor portion is integrated directly on the substrate layer, then the structure is simple and manufacturing is easy, but the sensor is sensitive to external stresses transmitted through the substrate layer

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidmeasurement accuracy

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The substrate layer is segmented by creating a recess that divides the structure into a sensitive sensor portion and a stress-transmitting substrate portion. This segmentation allows the sensitive portion to be mechanically isolated from external stresses while maintaining the overall structural integrity and manufacturing simplicity of the sensor element.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a recess is created in the substrate layer to mechanically isolate the sensitive sensor portion, then stress sensitivity is reduced, but the structural complexity increases

Engineering Contradiction:

Improvestress isolationVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The recess is created only in the specific region where the sensitive sensor portion is located, rather than modifying the entire substrate layer. This local modification provides the necessary stress isolation while minimizing the overall structural complexity and maintaining the simplicity of the rest of the sensor element structure.

Inventive Principle:

Principle #3Local quality

3Reliability

If the recess extends deeply into the substrate layer, then mechanical isolation is improved, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvemechanical decouplingVSAvoidrecess depth control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The recess extends partially into the substrate layer, providing sufficient mechanical isolation without requiring complete penetration or excessive depth. This partial action achieves the necessary stress isolation effect while keeping the manufacturing precision requirements manageable and the structure practical for standard fabrication processes.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS7685881B2Sensor element and sensor assembly provided with a casing

Publication Date: 2010.03.30 MEASUREMENT SPECIALTIES INC

AI summary

A sensor element having a sensitive sensor portion on an upper side of a substrate layer. The upper side of the substrate layer is provided with a recess on the periphery of the sensitive sensor portion. The recess provides mechanical isolation or decoupling of the sensitive sensor portion, as a result of which external forces do not cause stress in the sensitive sensor portion. In addition, a sensor assembly is described which is provided with at least one sensor element and a casing.