MEMS Accelerometer Proof Mass Decoupling via Folded Springs
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Solution Overview
Problem
Conventional MEMS and IC technologies face challenges in increasing performance, reducing size, and decreasing cost, while also requiring more complex microsystems with greater computational power, which are not adequately addressed by existing methods.
Innovation Solution
The development of three-axis MEMS inertial sensor devices with dual or single proof mass configurations and parallel folded spring elasto-kinematics designs that decouple motion among axes, minimizing cross-axis sensitivity and parasitic coupling, and incorporating geometric symmetry to provide compact, error-free acceleration measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MEMS designs are used, then manufacturing is simpler, but cross-axis sensitivity and parasitic coupling increase measurement errors
Solution Approach 1:
The spring structure is divided into multiple folded segments (first folded spring, second folded spring, third folded spring, fourth folded spring) that are arranged in a specific geometric pattern. This segmentation allows each spring to independently handle specific motion components, thereby decoupling the axes and reducing cross-axis sensitivity while maintaining manufacturing feasibility through repetitive modular elements.
Solution Approach 2:
The spring structures exhibit asymmetric folding patterns where the first and second folded springs have different configurations from the third and fourth folded springs. This asymmetry is deliberately designed to create geometric symmetry in the overall assembly, which cancels out parasitic coupling effects and minimizes measurement errors across different measurement axes.
2Volume of moving object
If dual or single proof mass configurations are used, then device size is reduced, but decoupling motion among axes becomes more challenging
Solution Approach 1:
The spring structures are nested within each other in a concentric arrangement, with inner springs positioned within the boundaries of outer springs. This nesting allows multiple spring elements to occupy overlapping spatial regions, significantly reducing the overall device volume while maintaining the structural integrity and functional independence needed for axis decoupling.
Solution Approach 2:
The spring structures utilize three-dimensional folding patterns that extend in multiple spatial dimensions. By arranging springs in a vertically stacked, nested configuration rather than a planar layout, the design achieves compact volume while preserving the mechanical independence of each measurement axis through careful orientation of spring folds in different dimensional planes.
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 solution results in compact, error-free MEMS inertial sensor devices capable of providing accurate acceleration measurements across multiple decoupled degrees of freedom, enhancing performance and reducing size and cost while maintaining computational efficiency.
Implementation Method 1
a spring structure (130) coupled to the proof mass structure (110, 210) and the anchor structure (140)
Data Source
AI summary
An integrated MEMS inertial sensor device includes one or more three-axis MEMS inertial sensor devices, such as accelerometers, with dual or single proof mass configurations. These designs can be compact and can decouple the motion of each axis to minimize the measurement errors due to cross-axis sensitivity. Some embodiments include a frame to decouple the motion of two axes and to provide geometric symmetry. Some embodiments also include double-folded springs. In a specific embodiment, the three axes of an integrated MEMS accelerometer device are entirely decoupled. Thus, the actuation of each axis, through a force due to acceleration, has little or substantially no effect on the other axes.