MEMS Sensor Pressure Compensation via Reference Membrane
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Solution Overview
Problem
MEMS sensors face challenges in accurately measuring fluid constituents due to influences from ambient pressure and temperature, which can lead to measurement errors and inaccuracies.
Innovation Solution
A method involving a MEMS sensor with a suspended membrane whose resonant frequency is influenced by ambient pressure, where an evaluation device performs measurements based on the resonant frequency and accounts for ambient pressure to compensate for its effects, allowing for precise measurement of fluid constituents by combining results from different membrane sensitivities and using non-resonant readouts for temperature and pressure calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resonant frequency of the membrane is used to measure fluid constituents, then measurement sensitivity is improved, but measurement precision deteriorates due to influences from ambient pressure and temperature
Solution Approach 1:
The patent introduces a reference membrane as an intermediary element that experiences the same ambient pressure and temperature influences as the sensing membrane. By measuring the resonant frequency shift of the reference membrane, the system can isolate and subtract the environmental interference from the total measured signal, thereby recovering the pure fluid constituent signal and improving measurement precision.
Solution Approach 2:
The patent implements a feedback mechanism where the evaluation device continuously monitors the resonant frequency of both the sensing membrane and reference membrane. The system uses the reference membrane's frequency response to dynamically compensate for environmental variations in real-time, adjusting the measurement calculation to maintain high precision despite changing ambient conditions.
2Adaptability or versatility
If multiple membranes with different sensitivities are used, then adaptability to different fluid constituents is improved, but device complexity increases
Solution Approach 1:
The patent designs a universal sensing platform where multiple membranes with different sensitivities are integrated into a single MEMS device structure. This multi-functional design allows the same device to detect various fluid constituents by selectively activating different membranes, eliminating the need for multiple separate sensor devices and reducing overall system complexity.
Solution Approach 2:
The patent segments the sensing function into separate membrane elements, each optimized for specific fluid constituents. By dividing the sensing task among multiple specialized membranes within a unified device architecture, the system achieves high adaptability while maintaining manageable complexity through modular design and shared readout circuits.
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 enables precise and accurate measurement of fluid constituents by compensating for ambient pressure and temperature influences, reducing errors and allowing for precise determination of fluid properties, such as humidity and gas concentrations, while maintaining a compact and efficient design.
Implementation Method 1
contacting the membrane with a fluid such that the membrane adsorbs a fluid constituent
Implementation Method 2
the resonant frequency of said membrane being influenced by an ambient pressure that acts on the membrane
Data Source
AI summary
In accordance with an embodiment, a MEMS sensor includes a membrane that is suspended from the substrate, a resonant frequency of said membrane being influenced by an ambient pressure that acts on the membrane; and an evaluation device configured to perform a first measurement based on the resonant frequency of the membrane to obtain a measurement result, where the evaluation device is configured to at least partly compensate an influence of the ambient pressure on the measurement result.