MEMS Calibration via Electrical Stimulus and Feedback
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Solution Overview
Problem
Existing methods for calibrating and testing Microelectromechanical Systems (MEMS) devices are costly, time-consuming, and require physical stimuli, which can lead to system malfunctions over time due to changes in electro-mechanical characteristics, and necessitate costly re-calibration and maintenance.
Innovation Solution
A system and method for electrical testing and calibration of MEMS devices that allows for continuous monitoring and recalibration without the need for external physical forces, using a sensor-responsive system with a microcontroller, capacitance-to-voltage circuitry, and calibration algorithms to adjust trim values based on the device's characteristics, enabling real-time calibration and reduced maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical stimuli are used for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces physical stimulus application with electrical signal-based calibration. The microcontroller applies electrical signals to the MEMS device and measures the electrical response, eliminating the need for physical calibration equipment and manual physical stimulus application. This substitution reduces system complexity while maintaining calibration accuracy.
Solution Approach 2:
The MEMS device performs self-calibration by measuring its own electrical response to applied signals. The device's built-in sensor detects changes in capacitance or resistance caused by electrical stimulation, allowing the device to calibrate itself without external intervention. This self-service approach reduces the need for complex external calibration systems.
2Measurement precision
If physical stimuli are applied for testing, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent enables continuous calibration by applying electrical signals continuously or in rapid succession without interruption to the device's operational state. The microcontroller can perform multiple calibration cycles sequentially, and the device can be calibrated during normal operation, eliminating downtime associated with physical calibration procedures.
Solution Approach 2:
Electrical signal-based calibration allows for rapid, automated measurement cycles that can be performed continuously. The digital signal processing and automated data collection eliminate manual measurement steps, significantly reducing the time required for each calibration cycle compared to physical stimulus methods.
3Measurement precision
If physical stimuli are used for calibration, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent implements feedback-based calibration where the microcontroller measures the electrical response of the MEMS device and uses this information to adjust calibration parameters. The feedback loop allows the system to compensate for manufacturing variations by adapting to the actual device characteristics, reducing the stringency of manufacturing precision requirements.
Solution Approach 2:
The calibration process dynamically adjusts electrical parameters such as signal frequency, amplitude, and timing to optimize the measurement. By changing these parameters during calibration, the system can achieve accurate measurements even when manufacturing tolerances vary, as the parameters are adapted to match the specific device characteristics.
4Reliability
If repeated physical calibration is performed, then reliability is improved, but loss of time and cost increase
Solution Approach 1:
The device performs self-diagnosis and self-calibration by monitoring its own performance and automatically adjusting calibration parameters when drift or degradation is detected. This eliminates the need for manual intervention and reduces maintenance time, as the device can be recalibrated quickly during operation without requiring physical calibration equipment or downtime.
Solution Approach 2:
The patent enables continuous monitoring and calibration without interrupting device operation. The microcontroller can perform calibration routines during normal operation, allowing repeated calibration cycles to be performed continuously rather than requiring scheduled maintenance downtime. This continuous approach improves reliability while minimizing time loss.
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
Enables low-cost, repeated testing and recalibration of MEMS devices throughout their lifetime without removal from the system, improving reliability and reducing maintenance costs by maintaining accurate calibration despite changes in electro-mechanical characteristics.
Implementation Method 1
capacitive-sensing MEMS designs are highly desirable for operation in acceleration, angular rotation, pressure environments and in miniaturized devices due to their relatively low cost. When subjected to acceleration, angular rotation, pressure, or some other external stimulus to which the MEMS device is designed to be responsive, capacitive sensing MEMS devices provide a change in electrical capacitance that corresponds to the magnitude of the applied stimulus.
Data Source
AI summary
A sensor system includes a microelectromechanical systems (MEMS) sensor, a processor, measurement circuitry, stimulus circuitry and memory. The MEMS sensor is configured to provide an output responsive to physical displacement within the MEMS sensor to the measurement circuitry. The stimulus circuitry is configured to provide a stimulus signal to the MEMS sensor to cause a physical displacement within the MEMS sensor. The measurement circuitry is configured to process the output from the MEMS sensor and provide it to the processor. The processor is configured to generate stimulus signals and provide them to the stimulus circuitry for provision to the MEMS sensor. The processor is configured to monitor the output from the measurement circuitry corresponding to the physical displacement occurring in the MEMS sensor, calculate MEMS sensor characteristics based on the output, and update calibration values based on the output. Methods for monitoring and calibrating MEMS sensors are also provided.