MEMS Component with Stop Element for Squeeze-Film Damping
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Solution Overview
Problem
MEMS microphones with a dual membrane structure face limitations due to high mechanical stiffness, which restricts deflection, sensitivity, and signal-to-noise ratio.
Innovation Solution
A MEMS component with a substrate having a cavity and base, featuring an interaction element with a bending beam, boundary layer, and backplate. The interaction element includes a stop element that can be displaced into a mechanical stop, creating a fluid flow resistance and minimizing fluidic squeeze-film damping effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dual membrane structure is used to improve signal-to-noise ratio, then fluidic damping is reduced, but mechanical stiffness increases which limits deflection and sensitivity
Solution Approach 1:
The interaction element is divided into a bending beam and a separate boundary layer connected by connecting elements. This segmentation allows the bending beam to deflect independently while the boundary layer provides structural support, resolving the contradiction between needing flexibility for sensitivity and stiffness for structural integrity.
Solution Approach 2:
Connecting elements serve as intermediaries between the bending beam and boundary layer, allowing controlled mechanical coupling that balances deflection capability with structural stability, thereby maintaining both sensitivity and signal-to-noise ratio.
2Length of moving object
If the stop element is not engaged in the mechanical stop, then deflection is maximized, but fluid leakage and gap noise increase
Solution Approach 1:
The stop element can dynamically transition between engaged and disengaged states. During normal operation, it remains disengaged to allow maximum deflection. During rapid pressure changes, it engages to seal gaps and prevent fluid leakage, adapting to operational conditions in real-time.
Solution Approach 2:
The stop element is pre-positioned near the mechanical stop so that during rapid differential pressure changes, it can quickly engage to prevent fluid leakage and gap noise before significant harmful effects occur.
3Reliability
If fluidic squeeze-film damping effects are present, then fluid leakage occurs and sensitivity is reduced, but eliminating them requires complex sealing structures
Solution Approach 1:
The harmful fluidic squeeze-film damping effects are extracted or removed by engaging the stop element to create a fluid seal, separating the acoustic chamber from the cavity and eliminating the harmful fluid coupling while maintaining structural integrity.
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 design enhances sensitivity and signal-to-noise ratio by maximizing deflection and minimizing fluid leakage and gap noise, allowing for either smaller size with the same performance or higher performance with the same size compared to related art.
Implementation Method 1
the stop element in the stop causes at least one fluid flow resistance, in particular a fluid seal, between the cavity on a side facing the substrate and a volume on a side of the hollow space facing away from the substrate
Implementation Method 2
at least one electrode, which forms one or more readable capacitances with the back electrode of the backplate, in order to capacitively detect a deflection of at least one of the bending beam and the connecting elements and the boundary layer
Implementation Method 3
fluidic squeeze-film damping effects are avoided in an advantageous manner
Data Source
AI summary
A MEMS component. The MEMS component includes: a substrate having a cavity and a base, an interaction element arranged above the cavity and connected to the base, including a bending beam, a boundary layer at a distance from the bending beam via connecting elements and defining a hollow space with the bending beam, and a backplate within the hollow space, the backplate being stiffer in relation to the boundary layer and the bending beam, at least one electrode, which forms a readable capacitance with a back electrode of the backplate, to capacitively detect a deflection of at least one of the bending beam, the connecting elements and the boundary layer, at least one stop element, configured to be displaced into a mechanical stop.