Acceleration Sensor Elastic Structure Resonance Frequency
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Solution Overview
Problem
Existing acceleration sensors face challenges in miniaturization and the need for a wider range of detectable acceleration and higher resonance frequencies to effectively measure high-frequency acceleration changes, which are not adequately addressed by current technologies.
Innovation Solution
The acceleration sensor design incorporates a semiconductor substrate with a cavity, a floating fixed structure, and a movable structure supported by an elastic structure featuring rectilinear portions with reinforcing frames, allowing for increased resonance frequency and broader detectable acceleration ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the acceleration sensor is miniaturized using MEMS technology, then the device size is reduced, but the resonance frequency of the movable portion decreases
Solution Approach 1:
The elastic structure is divided into multiple segments including a beam portion and a post portion, with the post portion providing vertical support and the beam portion providing horizontal flexibility. This segmentation allows the sensor to maintain high resonance frequency while being miniaturized.
Solution Approach 2:
Different portions of the elastic structure have different structural characteristics - the post portion is designed for vertical support with specific dimensions, while the beam portion is designed for horizontal flexibility with different dimensions. This local differentiation optimizes both resonance frequency and miniaturization.
2Adaptability or versatility
If the resonance frequency is increased to detect high-frequency acceleration changes, then the detectable acceleration range is improved, but the device complexity increases
Solution Approach 1:
The elastic structure serves multiple functions simultaneously: it supports the movable portion vertically, provides horizontal flexibility for acceleration detection, and is designed with specific dimensional ratios to achieve high resonance frequency. This multi-functionality reduces the need for additional components.
Solution Approach 2:
The patent specifies particular dimensional parameters for the elastic structure, including the height-to-length ratio of the post portion and the width-to-length ratio of the beam portion. By optimizing these parameters, the resonance frequency is increased without requiring complex structural modifications.
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 enhances the resonance frequency of the movable portion, enabling the sensor to detect a wider range of accelerations, including high-frequency changes, thereby improving its measurement capabilities.
Implementation Method 1
a movable structure that includes a movable electrode supported by the semiconductor substrate via an elastic structure in a state of floating with respect to the cavity and displacing with respect to the fixed electrode
Implementation Method 2
a resonance frequency of vibration of a movable portion of an acceleration sensor must be made high
Data Source
AI summary
An acceleration sensor includes a semiconductor substrate that has a cavity formed in an interior, a fixed structure that includes a fixed electrode supported by the semiconductor substrate in a state of floating with respect to the cavity, and a movable structure that includes a movable electrode supported by the semiconductor substrate via an elastic structure in a state of floating with respect to the cavity and displacing with respect to the fixed electrode. The elastic structure includes a first end portion supported by the semiconductor substrate, a second end portion connected to the movable structure, and an intermediate portion connecting the first end portion and the second end portion and has a rectilinearly-extending rectilinear portion at least at a portion of the intermediate portion and the rectilinear portion includes a plurality of rectilinear frames extending in parallel to each other in a direction in which the rectilinear portion extends.