MEMS Sensor Anchoring Structure Decoupling Anchor Displacement

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Solution Overview

Problem

MEMS sensors, such as gyroscopes and accelerometers, face measurement errors due to manufacturing tolerances, installation, and environmental factors causing displacement of anchor points, which affects the relative locations of micromechanical components and leads to incorrect scaling and measurement errors.

Innovation Solution

The implementation of a suspended spring-mass system with anchoring structures that decouple active components from direct anchor displacement, using flexible springs and rigid masses to absorb undesired forces and maintain the components' location within the MEMS layer, ensuring accurate measurement by preventing displacement of the suspended spring-mass system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If direct anchoring of micromechanical components is used, then device complexity is reduced, but measurement precision deteriorates due to anchor displacement

Engineering Contradiction:
Improveanchoring structureVSAvoidmeasurement error
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary anchoring structure consisting of flexible anchors and rigid masses that decouple the active micromechanical components from the substrate. This intermediary structure absorbs anchor displacements and prevents them from being transmitted to the sensing components, thereby maintaining measurement precision while managing the complexity of the anchoring system.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If rigid anchoring is used, then structural stability is improved, but measurement precision deteriorates due to stress and force transmission to micromechanical components

Engineering Contradiction:
Improvestructural stabilityVSAvoidmeasurement error
Core Design Contradiction:
Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The patent applies different mechanical properties to different parts of the anchoring structure. The anchors are designed to be flexible to absorb displacements, while the rigid masses provide local stability and prevent stress transmission to the active components. This localized differentiation of mechanical properties allows the structure to simultaneously achieve stability and precision.

Inventive Principle:
Principle #3Local quality

3Adaptability or versatility

If flexible anchoring is used, then tolerance to anchor displacement is improved, but structural strength deteriorates

Engineering Contradiction:
Improvetolerance to displacementVSAvoidstructural strength
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The anchoring structure combines flexible and rigid elements in a composite configuration. The flexible anchors provide tolerance to displacement and stress, while the rigid masses provide structural strength and stability. This composite approach allows the system to simultaneously achieve adaptability to displacement and structural strength.

Inventive Principle:
Principle #40Composite materials

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

This solution significantly reduces measurement errors by maintaining the movable components' location within the MEMS layer, ensuring accurate sensing of parameters like linear acceleration and angular velocity, even under conditions that would otherwise cause displacement.

Implementation Method 1

The movable components are decoupled from the anchors by a plurality of springs and at least one rigid mass

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The movable components are decoupled from the anchors by a plurality of springs and at least one rigid mass

Methodology Applied
Scientific EffectInertia: Inertia

Data Source

PatentEP3583386B1Anchoring structure for a sensor insensitive to anchor movement
Publication Date: 2021.03.24 INVENSENSE INC
  • EP3583386B1 patent drawingFigure 1
  • EP3583386B1 patent drawingFigure 2
  • EP3583386B1 patent drawingFigure 3A~3C

AI summary

A MEMS sensor includes a substrate and a MEMS layer. A plurality of anchoring points within the MEMS layer suspend a suspended spring-mass system that includes active micromechanical components that respond to a force of interest such as linear acceleration, angular velocity, pressure, or magnetic field. Springs and rigid masses couple the active components to the anchoring points, such that displacements of the anchoring points do not substantially cause the active components within the MEMS layer to move out-of-plane.