MEMS Dynamic Parameter Extraction from Static Excitation
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Solution Overview
Problem
Existing methods for determining dynamic parameters of MEMS apparatuses are prone to errors due to high time resolution, over-damping, and poor mathematical conditioning, especially under critical circumstances, making it difficult to accurately measure frequency and damping without altering natural frequencies and damping values, particularly in highly integrated components with limited access for high-frequency analysis.
Innovation Solution
A method and device for determining dynamic parameters using static excitations of constant amplitude, combined with a model-based evaluation of response signals, allowing for precise calculation of dynamic properties through geometric and structural properties of movable components, even in over-damped systems and highly integrated MEMS devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dynamic tests with sinusoidal or periodic test signals are used to determine dynamic properties, then frequency characteristics can be measured, but measurement precision deteriorates due to high time resolution requirements and short averaging times
Solution Approach 1:
The patent inverts the conventional approach by determining dynamic parameters (resonance frequency, damping) through static or quasi-static measurements rather than dynamic excitation. Static test signals are applied to the MEMS apparatus, and dynamic parameters are derived from the static response characteristics and model parameters, eliminating the need for high-time-resolution dynamic measurements.
Solution Approach 2:
The patent performs preliminary static measurements to determine model parameters (such as spring constants, mass, geometric properties) before calculating dynamic parameters. This preliminary characterization of static properties enables subsequent derivation of dynamic characteristics without requiring actual dynamic excitation, thus reducing measurement time while maintaining precision.
2Measurement precision
If strong excitation stimuli are applied to determine dynamic properties, then dynamic parameters can be extracted, but natural frequencies and damping values are altered due to feedback mechanisms affecting the sensor structure
Solution Approach 1:
Instead of applying strong dynamic excitations to extract dynamic parameters, the patent uses weak or static excitations and inverts the problem: dynamic parameters are calculated from static model parameters rather than measured directly through strong dynamic testing. This prevents feedback mechanisms from altering the natural frequencies and damping values during measurement.
Solution Approach 2:
The patent creates a mathematical model (copy) of the MEMS apparatus that replicates its mechanical properties. By measuring static properties of this model and deriving dynamic parameters from it, the actual physical system is not subjected to strong excitations that would alter its natural characteristics, yet accurate dynamic parameters are obtained through the model.
3Measurement precision
If conventional dynamic testing methods are used for highly integrated MEMS components, then dynamic parameters can be determined, but device complexity increases due to limited access for high-frequency analysis equipment
Solution Approach 1:
The patent enables the MEMS apparatus to characterize its own dynamic properties through static measurements and model-based calculations, without requiring external high-frequency analysis equipment or complex test setups. The static test signals and evaluation can be performed with simple equipment, making the method self-sufficient and suitable for highly integrated components where access is limited.
Solution Approach 2:
The patent replaces complex mechanical/dynamic measurement systems with a simplified static measurement system combined with mathematical modeling. Instead of using bulky HF analysis equipment to directly measure dynamic properties, the method uses static or quasi-static electrical/mechanical measurements and computes dynamic parameters through model equations, significantly reducing measurement setup complexity.
4Loss of information
If frequency and damping parameters are extracted from noisy test data under critical circumstances, then dynamic characteristics can be obtained, but measurement precision deteriorates due to poor mutual mathematical conditioning
Solution Approach 1:
The patent performs preliminary determination of model parameters from static measurements before extracting dynamic parameters. By first establishing accurate static characteristics (spring constants, mass, geometric properties) under well-conditioned mathematical circumstances, the subsequent calculation of dynamic parameters avoids the poor mathematical conditioning that occurs when directly extracting frequency and damping from noisy dynamic data.
Data Source
AI summary
A method for ascertaining at least one dynamic parameter of a MEMS apparatus, which has at least one movable component, and the at least one dynamic parameter describes a dynamic property of the at least one movable component. A test signal which has at least one static excitation of constant amplitude is applied to the MEMS apparatus, and a response signal of the MEMS apparatus to the test signal is detected. At least one static parameter of the MEMS apparatus is ascertained by evaluating the response signal in respect of the at least one static excitation, using a model of at least the movable component of the MEMS apparatus, the at least one static parameter describing a geometric and/or structural property of the at least one movable component. The at least one dynamic parameter of the MEMS apparatus is calculated based on the ascertained at least one static parameter.