MEMS Inertial Sensor Inspection Electrodes Damping Holes
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Solution Overview
Problem
Existing acceleration sensors using silicon MEMS technology face high noise levels in stationary states, which degrade resolution and accuracy due to excessive damping, making it difficult to inspect movable bodies without compromising noise characteristics.
Innovation Solution
The inertial sensor design includes a base body, sensor element, and lid body with a movable body rotatable about a first axis, coupled by rotation springs, featuring a movable comb electrode group, fixed comb electrode group, and inspection electrodes with damping adjustment holes to reduce damping and enhance detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a first deflection electrode is provided for inspection purposes, then self-inspection capability is improved, but damping increases and noise characteristics deteriorate
Solution Approach 1:
The patent extracts the inspection function from the deflection electrode structure by providing separate first and second inspection electrodes that face each other across the movable body. This allows inspection without requiring deflection electrodes that would increase damping, thereby resolving the contradiction between self-inspection capability and noise characteristics.
Solution Approach 2:
The patent introduces an intermediary structure (the gap between first and second inspection electrodes) that enables inspection functionality without directly coupling the inspection mechanism to the movable body in a way that would increase damping. The inspection electrodes act as mediators that allow electrical testing without mechanical interference.
2Object-affected harmful factors
If damping is increased to reduce Brownian noise, then noise characteristics improve, but detection sensitivity deteriorates
Solution Approach 1:
The patent changes the structural parameters of the movable body by providing through-holes that reduce the mass and moment of inertia of the movable body. This allows the system to achieve low Brownian noise through reduced damping while maintaining detection sensitivity by optimizing the mass and rotational characteristics of the movable body.
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 configuration allows for easy inspection of movable bodies while maintaining low noise characteristics, improving detection sensitivity and reliability by balancing damping and detection sensitivity through strategically placed damping adjustment holes.
Implementation Method 1
a movable comb electrode group provided at the movable body, a fixed comb electrode group provided at the base body and facing the movable comb electrode group
Implementation Method 2
a first inspection electrode provided at the movable body, and a second inspection electrode provided at the base body or the lid body and overlapping the first inspection electrode in a plan view of the base body
Implementation Method 3
the first inspection electrode is provided with a plurality of damping adjustment holes
Data Source
AI summary
An inertial sensor includes: a base body; a sensor element provided at the base body; and a lid body covering the sensor element. The sensor element includes a anchor fixed to the base body, a movable body swingable about a first axis, which is horizontal to the base body, as a swing axis, a first rotation spring and a second rotation spring coupling the anchor and the movable body, a movable comb electrode group provided at the movable body, a fixed comb electrode group provided at the base body and facing the movable comb electrode group, a first inspection electrode provided at the movable body, and a second inspection electrode provided at the base body or the lid body and overlapping the first inspection electrode in a plan view. In the plan view, the first inspection electrode is provided with a plurality of damping adjustment holes.