MEMS Anchor Structure Aligning Rotor and Stator Points
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Solution Overview
Problem
MEMS devices, such as accelerometers, face measurement errors due to temperature-induced changes that cause relative movement between fixed and movable electrodes, leading to inaccurate acceleration measurements.
Innovation Solution
A MEMS device design featuring a rotor and stators anchored via overlapping anchor points along a common axis, minimizing relative movement between anchor points and improving measurement accuracy by ensuring uniform expansion/contraction effects across all anchor points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If anchor points are distributed across the substrate plane, then structural stability is improved, but temperature-induced relative movement between anchor points increases
Solution Approach 1:
The patent merges multiple anchor points (rotor anchor point and at least two stator anchor points) onto a single common axis, causing them to overlap when viewed from above. This consolidation reduces the spatial separation between anchor points, minimizing differential thermal expansion effects while maintaining structural stability through their combined anchoring function.
Solution Approach 2:
The patent employs asymmetric arrangement of stator anchor points relative to the rotor anchor point along the common axis. The stator anchor points are positioned at different locations along the axis, creating an asymmetric configuration that optimizes the cancellation of temperature-induced errors while maintaining structural integrity.
2Measurement precision
If stators are positioned on both sides of the rotation axis, then differential capacitance measurement is improved, but temperature-induced offset errors increase
Solution Approach 1:
The patent transitions from a two-dimensional symmetric arrangement (stators on both sides of the rotation axis) to a one-dimensional linear arrangement (all anchor points on a common axis). This dimensional change allows the stators to be positioned asymmetrically along the axis while maintaining their functional relationship, thereby reducing temperature-induced offset errors.
Solution Approach 2:
The common axis serves as an intermediary structure that organizes the rotor and stator anchor points in a linear sequence. This intermediate framework enables the asymmetric positioning of stators relative to the rotor along the axis, facilitating temperature error compensation while preserving differential measurement capability.
3Strength
If anchor points are positioned far apart, then mechanical stability is improved, but relative movement due to thermal expansion increases
Solution Approach 1:
The patent merges the anchor points onto a common axis, effectively reducing the projected distance between them in the substrate plane. This consolidation maintains mechanical stability through the combined anchoring function while minimizing the physical separation that would amplify differential thermal expansion effects.
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 reduces temperature-induced errors by aligning anchor points along a common axis, minimizing relative movement and enhancing the accuracy of acceleration measurements in MEMS devices.
Implementation Method 1
Movement of the proof mass is measured capacitively, with one or more moveable electrodes located on the proof mass and one or more fixed electrodes located on a fixed structure within the accelerometer. The fixed and moveable electrodes form one or more capacitors, the capacitance of which changes as the proof mass moves relative to the fixed structure.
Implementation Method 2
as the MEMS device experiences temperature changes, the relative positions of the fixed and moveable electrodes may change due to expansion or contraction within the device itself
Data Source
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AI summary
The present invention relates to microelectromechanical systems (MEMS), and more specifically to an anchor structure for anchoring MEMS components within a MEMS device. The anchor points for rotor and stator components of the device are arranged such that the anchor points are arranged along and overlap a common axis.