MEMS Mechanical Link Rotational to Translational Motion
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Solution Overview
Problem
Existing MEMS-NEMS sensors face challenges in achieving perfect differential measurement due to asymmetrical mechanical behavior of strain gauges, leading to parasitic constraints and reduced sensitivity, particularly in out-of-plane and in-plane detection configurations.
Innovation Solution
A mechanical connection that transforms rotational movement of a moving part into translational movement of a detection means, using a combination of pivot and sliding connections to minimize parasitic deformations and maintain symmetry, allowing for pure compression or tension on strain gauges without additional space constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If strain gauges are arranged asymmetrically in conventional MEMS-NEMS structures, then the structure can be simplified and easier to manufacture, but the differential measurement precision deteriorates due to parasitic constraints and asymmetrical mechanical behavior
Solution Approach 1:
The patent applies asymmetry in reverse - it deliberately creates a symmetric arrangement of strain gauges around the pivot axis to eliminate the harmful asymmetrical mechanical behavior that occurs in conventional structures. The strain gauges are positioned at symmetric locations (e.g., equal distances from the pivot axis) to ensure identical mechanical behavior under the same loading conditions, thereby achieving perfect differential measurement.
2Measurement precision
If strain gauges are positioned closer to the pivot axis to reduce parasitic constraints, then measurement accuracy improves, but the available space for gauge placement is reduced
Solution Approach 1:
The patent utilizes the out-of-plane dimension (z-direction) to position strain gauges at optimal locations that maintain symmetry while providing sufficient space. By arranging gauges in a three-dimensional configuration around the pivot axis rather than constraining them to a single plane, the design achieves both measurement accuracy and adequate space for gauge placement.
3Device complexity
If conventional pivot connections are used without transformation mechanisms, then the device complexity is reduced, but the ability to transform rotational movement into translational movement for detection is lost
Solution Approach 1:
The patent creates a multi-functional mechanical connection that simultaneously serves as a pivot connection (allowing rotation) and as a movement transformation mechanism (converting rotation to translation). The strain gauges are arranged to detect both rotational and translational components, making the same structural elements serve multiple detection functions without adding separate transformation mechanisms.
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 enhances the symmetry of differential measurements, reduces parasitic constraints, and improves the accuracy of strain gauge readings by ensuring gauges experience only intended compression or tension, thereby enhancing the sensitivity and reliability of MEMS-NEMS sensors.
Implementation Method 1
two first beams 3.1, 3.2 aligned with the pivot axis Y, connected at each of their ends to the fixed part 2 and to the moving part 4, and working in torsion around the axis Y
Implementation Method 2
two second beams 5.1, 5.2 arranged perpendicular to the pivot axis Y, connecting the fixed part 2 to the moving part 4, and working in angular bending around the axis Y
Implementation Method 3
The structure S also includes means for detecting the movement of the moving part 4 relative to the fixed part 2 which are formed by strain gauges 6
Data Source
Figure 1~2A
Figure 2B~2C
Figure 3~4B
AI summary
The invention relates to a mechanical link for a microelectromechanical and/or nanoelectromechanical structure, said structure comprising a moving part, a fixed part extending along a principal plane and means for detecting the displacement of the moving part relative to the fixed part, said mechanical link comprising: - a first link connected to the fixed part and to the moving part and capable of allowing the rotation of said moving part relative to said fixed part around an axis of rotation; - a second link connecting the moving part to the detection means at a given distance relative to the axis of rotation in a direction perpendicular to said axis of rotation; - a third link connected to the fixed part and to the detection means, and configured to guide said detection means in translation along a direction of translation in the plane of the fixed part;so that the combination of the second and third links is capable of transforming the rotational movement of the moving part into a translational movement of the detection means along the direction of translation.