Inertial Sensor Electrode Spacing for Sensitivity and Damping
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Solution Overview
Problem
Existing inertial sensors face challenges in achieving both high detection sensitivity and desired frequency characteristics due to the trade-off between capacitance and air resistance, as altering the separation distance between the movable element and detection electrodes affects both sensitivity and damping.
Innovation Solution
The inertial sensor design includes a movable element with symmetrical and asymmetrical sections and strategically positioned dummy electrodes, which increase the separation distance between the movable element and dummy electrodes, enhancing capacitance and reducing air resistance, thereby improving sensitivity while maintaining desired frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the separation distance between the movable element and the first detection electrode is decreased to improve capacitance and acceleration detection sensitivity, then the capacitance increases and detection sensitivity improves, but the air resistance between the movable element and the dummy electrode increases, causing damping of the movable element and degrading frequency characteristics
Solution Approach 1:
The patent introduces a new spatial dimension by positioning the dummy electrode farther from the swing axis than the detection electrode. This dimensional arrangement allows the dummy electrode to be located at a greater separation distance from the movable element, reducing air resistance damping while the detection electrode maintains optimal proximity for high capacitance and sensitivity. The asymmetric positioning in the plan view along the axis-Z direction resolves the contradiction by exploiting spatial dimensionality.
Solution Approach 2:
The patent applies different separation distances to different electrodes based on their specific functions. The detection electrode is positioned closer to the movable element for high capacitance and sensitivity, while the dummy electrode is positioned farther away for low air resistance and minimal damping. This local differentiation of electrode positions allows each electrode to optimize its performance according to its specific role, resolving the contradiction between sensitivity and damping.
2Reliability
If the separation distance between the movable element and the first detection electrode is increased to reduce air resistance and damping, then the frequency characteristics improve, but the capacitance decreases, reducing acceleration detection sensitivity
Solution Approach 1:
The patent resolves this contradiction by introducing a new spatial dimension - positioning the dummy electrode farther from the swing axis than the detection electrode. This allows the detection electrode to maintain optimal proximity for high capacitance and sensitivity while the dummy electrode is positioned at a greater separation distance to reduce air resistance damping, achieving both high sensitivity and good frequency characteristics simultaneously.
Solution Approach 2:
The patent applies differentiated separation distances to different electrodes based on their specific functions. The detection electrode is positioned closer to the movable element for high capacitance and sensitivity, while the dummy electrode is positioned farther away for low air resistance and minimal damping. This local differentiation allows each electrode to optimize its performance according to its specific role.
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 configuration allows for excellent detection sensitivity with a desired frequency band, ensuring effective acceleration detection while minimizing damping and air resistance.
Implementation Method 1
When acceleration in the axis-Z direction acts on the inertial sensor, the movable element performs the seesaw swing around the swing axis
Implementation Method 2
the capacitance between the first movable section and the first detection electrode and the capacitance between the second movable section and the second detection electrode change accordingly
Implementation Method 3
since the separation distance between the movable element and the dummy electrode also decreases, the air resistance therebetween increases, so that damping of the movable element is likely to occur
Data Source
AI summary
An inertial sensor includes a movable element including a first movable section and a second movable section, a first detection electrode, and a first dummy electrode. The first movable section has a first section, a second section that is farther from the swing axis than the first section, and a third section disposed between the first section and second section. A separation distance between the third section and the first dummy electrode is greater than a separation distance between the first section and the first detection electrode.