MEMS Sensor Electrode Control for Resonant Frequency Stability
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Solution Overview
Problem
Existing sensors using MEMS structures face challenges in maintaining consistent vibration characteristics due to manufacturing process variations, leading to inaccuracies in acceleration detection.
Innovation Solution
A sensor design with a controller that controls potential differences between fixed and movable electrodes to stabilize resonant frequencies, using AC voltages to correct variations and enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If MEMS structure is used for sensor, then device complexity is reduced and manufacturing is simplified, but manufacturing process variations cause inconsistent vibration characteristics and detection inaccuracies
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the potential difference between fixed and movable electrodes through DC voltage application. This changes the mechanical properties of the beam (stiffness, resonant frequency) to compensate for manufacturing variations. The controller measures actual resonant frequency and adjusts voltage parameters to achieve target characteristics, resolving the contradiction between easy MEMS manufacturing and consistent vibration properties.
2Ease of manufacture
If manufacturing process variations are present, then production cost and ease of manufacture improve, but resonant frequency varies and detection accuracy deteriorates
Solution Approach 1:
The patent implements feedback control where the controller measures the actual resonant frequency of the beam using AC voltage excitation, compares it to the target frequency, and adjusts the DC voltage to the fixed electrode accordingly. This closed-loop feedback system compensates for manufacturing variations in resonant frequency, ensuring accurate acceleration detection despite production flexibility and varying manufacturing conditions.
3Measurement precision
If resonant frequency is adjusted to match target value, then detection accuracy improves, but additional control operations and device complexity increase
Solution Approach 1:
The patent applies self-service by enabling the sensor system to automatically measure its own resonant frequency and adjust its own operating parameters through the controller. The system performs self-diagnosis and self-correction by detecting frequency deviations and applying appropriate DC voltage adjustments, reducing the need for external calibration or complex manual control while improving detection accuracy.
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 design stabilizes resonant frequencies, enabling accurate and precise acceleration detection by reducing the effects of manufacturing non-uniformities and thermomechanical noise.
Implementation Method 1
The controller is configured to apply a first AC voltage between the first fixed electrode and the first movable electrode
Implementation Method 2
The controller is configured to control a first potential between the first other fixed electrode and the first other movable electrode
Data Source
AI summary
According to one embodiment, a sensor includes an element section, and a controller. The element section including a base, a first fixed portion, a first other fixed portion, a first fixed electrode, a first other fixed electrode, and a first movable member. The first movable member includes a first movable base supported by the first other fixed portion, a first beam, and a first movable structure. The first movable structure includes a first movable electrode, a first other movable electrode, and a first movable connecting portion. The controller performs first and second operations. The controller is configured to control a first potential between the first other fixed electrode and the first other movable electrode in the first operation. The controller is configured to apply a first AC voltage between the first fixed electrode and the first movable electrode in the second operation.