MEMS Transducer Diaphragm Gap for Sensitivity
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Solution Overview
Problem
Current MEMS transducer systems for pressure and acoustic sensing face challenges in achieving high sensitivity and dynamic range while minimizing parasitic capacitance and curvature-related issues.
Innovation Solution
The MEMS transducer system incorporates a diaphragm structure with a spacer and pressure sensing electrodes, where posts couple the diaphragms, and a barrier is applied to the diaphragm surfaces to reduce parasitic capacitance and enhance mechanical stability, allowing for increased sensitivity and linearity in pressure and acoustic signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional MEMS transducer structure is used, then the device can detect pressure and acoustic signals, but parasitic capacitance increases and sensitivity decreases
Solution Approach 1:
The device is divided into two separate diaphragms (first and second diaphragms) spaced apart to define a gap. This segmentation allows the pressure sensing electrode to be positioned within the gap adjacent to one diaphragm while the other diaphragm serves as a reference, reducing parasitic capacitance between the sensing electrode and the diaphragm surface while maintaining acoustic coupling.
Solution Approach 2:
The pressure sensing electrode is positioned within the gap between the two diaphragms rather than being placed directly on or immediately adjacent to a single diaphragm surface. This three-dimensional arrangement within the gap reduces parasitic capacitance while maintaining sensitivity to pressure and acoustic signals through the combined effect of both diaphragms.
2Ease of manufacture
If the diaphragm structure is simplified, then manufacturing is easier, but mechanical stability and linearity deteriorate
Solution Approach 1:
The first and second diaphragms are coupled together through spacers and posts to form a integrated diaphragm assembly. This merging of two diaphragms with a defined gap between them provides mechanical stability and linearity while maintaining a manufacturable structure using standard MEMS fabrication techniques.
Solution Approach 2:
Spacers and posts are introduced as intermediary elements to couple the first and second diaphragms at defined locations. These intermediaries provide mechanical support and maintain the gap structure, enhancing mechanical stability and linearity without complicating the manufacturing process.
3Measurement precision
If the gap between diaphragms is reduced to increase sensitivity, then parasitic capacitance increases and curvature effects worsen
Solution Approach 1:
The pressure sensing electrode is positioned adjacent to only one diaphragm (either the first or second diaphragm) within the gap, rather than being equidistant from both. This local positioning reduces parasitic capacitance and minimizes curvature effects while maintaining sensitivity through the localized electric field interaction.
4Object-generated harmful factors
If a barrier is applied to diaphragm surfaces, then parasitic capacitance is reduced, but manufacturing complexity increases
Solution Approach 1:
The barrier layer applied to the diaphragm surfaces serves multiple functions: it reduces parasitic capacitance between the diaphragm and pressure sensing electrode, provides mechanical reinforcement to the diaphragms, and can serve as part of the structural coupling mechanism. This multi-functionality reduces manufacturing complexity despite the additional layer.
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 configuration enhances the sensitivity and dynamic range of the MEMS transducer system by reducing parasitic capacitance and stabilizing the diaphragms, improving the overall performance in detecting pressure and acoustic signals.
Implementation Method 1
a pressure sensing electrode formed within the gap wherein the pressure sensing electrode is located adjacent to at least one of the first or the second diaphragm
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A MEMS transducer system includes a MEMS transducer device for sensing at least one of pressure signal or acoustic signal. The MEMS transducer device includes first and second diaphragms. Formed between the diaphragms are a spacer, plate capacitor elements, and electrode elements. The plate capacitor elements are coupled to the diaphragms via the spacer. An optional member may be disposed within the spacer. The distal ends of the electrode elements are coupled to a structure such as insulator element. An optional oxides may be formed within the plate capacitor elements. Pressure sensing electrode formed between the diaphragms may be coupled to the insulator element.