Capacitive Diaphragm Bridge Spring Structure for High Compliance
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Solution Overview
Problem
Traditional microphone element designs face limitations in diaphragm compliance and deformation, with existing structures either prone to fracture or having complex processing difficulties, which restrict their ability to achieve high resonant frequency responses and effective sound pressure sensing.
Innovation Solution
A miniature acoustic transducer design featuring a capacitive sound pressure-sensing element with a bridge-like spring structure, incorporating indentations on the diaphragm to create a support structure that increases compliance and deformation, allowing for enhanced capacitance variation sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional microphone element structures are used, then manufacturing simplicity is maintained, but diaphragm compliance and deformation are insufficient
Solution Approach 1:
The diaphragm is segmented into multiple regions including a central region, annular region, and finger-like protrusions. This segmentation allows different portions of the diaphragm to deform independently, increasing overall compliance while maintaining a relatively simple integrated structure that can be manufactured using standard MEMS processes.
Solution Approach 2:
The diaphragm incorporates curved and corrugated geometries, including finger-like protrusions and annular regions with varying thickness profiles. These curved structures increase the diaphragm's ability to deform under sound pressure while maintaining structural integrity, resolving the contradiction between compliance and simplicity.
2Measurement precision
If diaphragm deformation is increased to improve sound pressure sensing, then capacitance variation is enhanced, but the diaphragm becomes prone to fracture
Solution Approach 1:
The diaphragm features non-uniform thickness distribution with thicker regions at the periphery and thinner regions in the center and finger-like protrusions. This local quality variation allows high deformation in specific areas for improved sensing while maintaining structural strength in other regions, preventing fracture under acoustic stress.
Solution Approach 2:
The microphone element employs a composite structure combining the diaphragm with a backplate, separated by an air gap. This composite design distributes mechanical stress across multiple components, enhancing the diaphragm's durability while maintaining its ability to deform for accurate sound pressure sensing.
3Ease of manufacture
If a simple circular diaphragm design is used, then manufacturing is easier, but effective deformation amount and compliance are inadequate
Solution Approach 1:
The diaphragm is divided into functional zones including a central region, annular region, and multiple finger-like protrusions. This segmentation can be achieved through straightforward photolithography patterning processes, maintaining manufacturing simplicity while dramatically increasing effective deformation area and compliance compared to a simple circular design.
Solution Approach 2:
The diaphragm design transitions from a two-dimensional circular plane to a three-dimensional structure with finger-like protrusions and varying thickness profiles. This dimensional complexity is achieved through standard MEMS fabrication techniques such as anisotropic etching and layer deposition, maintaining ease of manufacture while enhancing deformation capability.
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 significantly increases diaphragm compliance and deformation, resulting in improved sound pressure sensing capabilities and higher capacitance variation, effectively addressing the limitations of traditional microphone structures.
Implementation Method 1
a capacitive sound pressure-sensing element, which includes a diaphragm and a back plate separated by an air gap to constitute a capacitor
Implementation Method 2
a spring structure provided on at least one of the other parallel plates
Data Source
AI summary
A technique using a new diaphragm structure and support design is provided herein for microphones or structure designs for pressure sensing. The structure includes a set of capacitive structures. The capacitive structure has a combination of a diaphragm structure, a back plate structure and a surrounding micro-structure for fixing the diaphragm. After the diaphragm structure has deformed due to a pressure load, a gap between the back plate and the diaphragm is changed accordingly, and variation occurs in the capacitance value between the two parallel plates. By using the principle of the effect of capacitance value variation, the capacitive sensor causes the capacitance value to vary with the change in the sound, thus accomplishing the object of measuring.