MEMS Accelerometer Hermeticity Detection via Test Signal
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Solution Overview
Problem
MEMS devices, such as accelerometers, face accuracy compromise due to hermetic seal failure, leading to fluid loss and environmental interference, which affects their operation and accuracy.
Innovation Solution
A method and system for determining hermeticity by applying a test signal above the operational frequency range to the accelerometer, filtering the output signal, and comparing its amplitude to a threshold to detect any deviation, thereby distinguishing between hermeticity loss and sensor breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MEMS device is hermetically sealed to maintain a desired atmosphere and environment, then the operational accuracy and reliability are improved, but the ability to detect hermeticity loss during operation is compromised
Solution Approach 1:
The patent applies preliminary action by incorporating a test signal injection capability and frequency response analysis mechanism into the MEMS device before actual operation. The system pre-establishes the relationship between hermeticity status and frequency response characteristics, enabling real-time detection without requiring external testing equipment or device disassembly.
Solution Approach 2:
The patent implements feedback by continuously monitoring the frequency response of the MEMS device through test signals and comparing the measured response against expected characteristics. When hermeticity loss is detected through frequency response analysis, the system can trigger alerts or corrective actions, creating a closed-loop monitoring system that maintains reliability.
2Reliability
If a test signal is applied to detect hermeticity, then real-time monitoring capability is improved, but the operational frequency range and accuracy are worsened
Solution Approach 1:
The patent applies periodic action by injecting test signals at specific intervals rather than continuously, and by using frequency domain separation where the test signal frequency is distinct from the operational frequency range. This periodic, frequency-separated approach allows the system to monitor hermeticity while minimizing interference with normal acceleration sensing operations.
Solution Approach 2:
The system performs preliminary frequency response characterization during manufacturing or calibration phases, establishing baseline responses for different hermeticity conditions. This pre-established knowledge base enables the operational system to quickly assess hermeticity status without requiring extensive real-time testing, thus minimizing impact on operational 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
This approach allows for real-time monitoring of hermeticity during operation, ensuring the accuracy of MEMS devices by differentiating between hermeticity loss and other faults, thus maintaining the pristine environment and operational integrity.
Implementation Method 1
A test signal having an associated frequency above an operational frequency range for the accelerometer is provided to the accelerometer
Implementation Method 2
The output signal of the accelerometer is filtered at least above the operational frequency range of the accelerometer producing a test output signal
Data Source
AI summary
Determining if a hermetically sealed MEMs device loses hermeticity during operation. In one embodiment, the MEMs device is an accelerometer. A test signal having an associated frequency above an operational frequency range for the accelerometer is provided to the accelerometer at an input during operation of the accelerometer for sensing an acceleration. The output signal of the accelerometer is filtered at least above the operational frequency range of the accelerometer producing a test output signal. The test output signal is then compared to a predetermined threshold to determine if the amplitude of the test output signal differs from the threshold. If the amplitude of the test output signal differs from the predetermined threshold, an error signal is produced indicating that hermeticity of the accelerometer has been lost.