Diaphragm Stress Sensor Structure with Vertical Protrusions for Linearity

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Solution Overview

Problem

Existing stress sensing elements with long cantilever beams or thin membranes suffer from non-linearity between resistance and stress, low yield, and increased cost due to large deformations.

Innovation Solution

A stress sensing element design featuring a substrate with through holes, a structured silicon layer with protrusion elements, and a top silicon layer with a supported and suspended region, including stress sensing units, which are supported by an outer frame and diaphragm, to enhance sensitivity and reduce deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a long cantilever beam or thin membrane is used to sense tiny changes, then sensitivity is improved, but non-linearity between resistance and stress increases due to large deformation

Engineering Contradiction:

ImprovesensitivityVSAvoidlinearity

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The diaphragm is divided into multiple protrusion elements (first, second, third protrusions) that segment the stress distribution. This segmentation allows the diaphragm to maintain high sensitivity through its overall structure while reducing local deformation non-linearity, thereby improving the linearity between resistance change and applied stress.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the diaphragm are designed with different geometries (protrusions of varying heights and positions) to optimize local stress distribution. The first protrusion has a different height than the second and third protrusions, creating local quality variations that enhance linearity while maintaining overall sensitivity.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If a long cantilever beam or thin membrane is used, then sensitivity is improved, but yield decreases due to large deformation

Engineering Contradiction:

ImprovesensitivityVSAvoidyield

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The diaphragm structure with multiple protrusions segments the deformation path, preventing excessive localized deformation that would lead to yield. The segmentation distributes stress more evenly across the structure, maintaining sensitivity while improving reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The protrusion elements act as pre-designed stress distribution features that cushion against excessive deformation before yield occurs. The geometric configuration of the protrusions provides inherent stress relief mechanisms that protect the structure from large deformations that would cause yield.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Measurement precision

If a long cantilever beam or thin membrane is used, then sensitivity is improved, but cost increases

Engineering Contradiction:

ImprovesensitivityVSAvoidcost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The diaphragm and protrusion elements are integrated into a single monolithic structure formed from the same substrate material. This merging eliminates the need for separate components and assembly steps, reducing manufacturing complexity and cost while maintaining the sensitivity-enhancing geometry.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention achieves sensitivity improvement through geometric parameter optimization (protrusion heights, positions, and shapes) rather than through material selection or complex multi-component assembly. This parameter-based approach simplifies manufacturing and reduces cost while maintaining high sensitivity.

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 design improves linearity, yield, and reduces vibration noise while maintaining sensitivity, allowing for more stable and cost-effective stress sensing.

Implementation Method 1

A resistance of a piezo-resistive sensor of the stress sensing element on a cantilever beam changes when stresses are developed in the cantilever beam

Methodology Applied

Scientific EffectPiezo-resistive effect: Piezoresistive Effect

Data Source

PatentUS20260036473A1Stress sensing element having diaphragm with vertical protrusions

Publication Date: 2026.02.05 ASIA PACIFIC MICROSYST

AI summary

A stress sensing element comprises a substrate, a structured silicon layer, a substrate connection layer attached to the substrate and the structured silicon layer, and a top silicon layer. The substrate comprises one or more through holes. The structured silicon layer comprises one or more protrusion elements, an outer frame, and a cavity connected to the one or more through holes of the substrate. The top silicon layer comprises a supported region, a suspended region, and one or more stress sensing units. The supported region of the top silicon layer is supported by the outer frame of the structured silicon layer. The suspended region comprises a diaphragm. The one or more stress sensing units sense stresses in the suspended region. The one or more protrusion elements of the structured silicon layer are attached to the diaphragm of the suspended region of the top silicon layer.