Inertial Sensor Comb Attenuator with Widened Finger Bases
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Solution Overview
Problem
Existing inertial sensors face issues with beam damage due to stress concentration at the base end portions when large accelerations are applied, as the beams have a cantilever configuration with constant width, leading to potential damage and reduced reliability.
Innovation Solution
The inertial sensor incorporates a comb-shaped attenuator with movable and fixed comb fingers, where the base ends of these fingers have a larger width than the tip ends, providing increased mechanical strength and reducing stress concentration, thereby preventing damage during collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the beams have a constant width in a cantilever configuration, then the structure is simple and easy to manufacture, but stress concentrates at the base end portion causing beam damage when large acceleration is applied
Solution Approach 1:
The beam width is made non-uniform along its length, with the base end portion having a larger width than the intermediate and tip end portions. This local variation in geometry concentrates mechanical strength where stress is highest (at the base), preventing beam damage while maintaining overall structural simplicity and manufacturability.
2Strength
If the beam width is increased at the base end portion, then the mechanical strength and stress distribution are improved, but the device complexity increases
Solution Approach 1:
The beam cross-sectional width varies locally along its length, being larger at the base end portion and smaller at intermediate and tip end portions. This localized geometric modification enhances mechanical strength and stress distribution without requiring complex overall structural changes, thus minimizing device complexity.
Solution Approach 2:
The beam width parameter is changed along the length of the beam, creating a tapered or stepped profile. This parameter variation optimizes the stress distribution and mechanical strength while maintaining a relatively simple structural form that does not significantly increase device complexity.
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 design effectively prevents damage to the comb fingers by distributing stress, enhancing the mechanical strength of the base end portions and improving detection accuracy by stabilizing unnecessary vibrations.
Implementation Method 1
an attenuator configured to attenuate a displacement of the movable body with respect to the substrate, in which the attenuator includes a comb-shaped first structure including a plurality of movable comb fingers whose base ends are coupled to the movable body, and a comb-shaped second structure including a plurality of fixed comb fingers whose base ends are coupled to the substrate, the plurality of fixed comb fingers meshing with the first structure
Data Source
AI summary
An inertial sensor includes: a substrate; a movable body configured to be displaced with respect to the substrate; and an attenuator configured to attenuate a displacement of the movable body with respect to the substrate. The attenuator includes a comb-shaped first structure including a plurality of movable comb fingers whose base ends are coupled to the movable body, and a comb-shaped second structure including a plurality of fixed comb fingers whose base ends are coupled to the substrate, the plurality of fixed comb fingers intersecting with the plurality of movable comb fingers. A width of the base end of each of the movable comb fingers and the fixed comb fingers is larger than a width of a tip end thereof.