MEMS Microphone Diaphragm Segmented Anchor Design
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Solution Overview
Problem
MEMS microphones with diaphragms anchored completely around their periphery tend to bow instead of moving uniformly, affecting sensitivity and sound quality due to internal tension and stress sensitivity.
Innovation Solution
A microphone design featuring a diaphragm assembly supported by a substrate with a carrier and springs that electrically isolate the diaphragm, allowing it to move uniformly and reducing stress effects, with an insulator between the substrate and carrier for capacitively coupling the diaphragm and substrate as a variable capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the diaphragm is anchored completely around its periphery, then the diaphragm is mechanically supported and stable, but the diaphragm bows instead of moving uniformly due to internal tension and stress
Solution Approach 1:
The continuous peripheral anchor is segmented into discrete anchor points or regions. The diaphragm is anchored at specific locations rather than continuously around the entire periphery, allowing the majority of the diaphragm surface to move uniformly in response to acoustic pressure while maintaining mechanical stability at the anchor points.
Solution Approach 2:
Different regions of the diaphragm are given different properties: the anchored regions provide mechanical stability and support, while the unanchored central regions are free to move uniformly. This local differentiation allows simultaneous achievement of stability and uniform movement.
2Strength
If the diaphragm is anchored completely around its periphery, then the diaphragm maintains structural integrity, but sensitivity and signal to noise ratio deteriorate due to bowing and stress effects
Solution Approach 1:
By segmenting the anchor into discrete points or regions rather than a continuous peripheral bond, the diaphragm can maintain sufficient structural integrity at the anchor locations while allowing the majority of the surface to move freely and uniformly, thereby improving sensitivity and reducing stress-induced noise.
Solution Approach 2:
The continuous anchor is extracted and replaced with discrete anchor points. This removal of the continuous constraint eliminates the bowing effect and internal tension that degrade sensitivity, while retaining enough mechanical support through the discrete anchors to maintain structural integrity.
3Shape
If a carrier and insulator are added to electrically isolate the diaphragm, then stress effects are reduced and movement uniformity improves, but device complexity increases
Solution Approach 1:
The carrier structure serves multiple functions simultaneously: it provides mechanical support for the diaphragm, acts as an electrical insulator to isolate the diaphragm from the substrate, and helps maintain the diaphragm's uniform movement. By combining these functions into a single integrated component, the overall device complexity is minimized.
Solution Approach 2:
The carrier is designed as a multi-functional component that performs both mechanical support and electrical insulation. This universal component eliminates the need for separate structures for each function, thereby improving diaphragm movement uniformity without proportionally increasing device complexity.
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
The design enhances diaphragm movement uniformity, improves sensitivity, and reduces stress-induced distortions, leading to better sound quality and mechanical integrity.
Implementation Method 1
an insulator between the substrate and the at least one carrier so as to electrically isolate the diaphragm and the substrate
Implementation Method 2
The diaphragm electrode and the fixed sensing electrode act like plates of a variable capacitor. During operation of the microphone, charges are placed on the diaphragm electrode and the fixed sensing electrode. As the diaphragm electrode vibrates in response to sound waves, the change in distance between the diaphragm electrode and the fixed sensing electrode results in capacitance changes that correspond to the sound waves.
Data Source
AI summary
A microphone includes a diaphragm assembly supported by a substrate. The diaphragm assembly includes at least one carrier, a diaphragm, and at least one spring coupling the diaphragm to the at least one carrier such that the diaphragm is spaced from the at least one carrier. An insulator (or separate insulators) between the substrate and the at least one carrier electrically isolates the diaphragm and the substrate.