MEMS Vibration Sensor with Nested Sensing Layers for Miniaturization
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Solution Overview
Problem
MEMS bone-conduction microphones face challenges with large size occupation and poor sensitivity, hindering product miniaturization.
Innovation Solution
A MEMS vibration sensor design featuring a substrate with a supporting portion and cavity, including sensing-units connected via dielectric materials and metal pads for enhanced sensitivity, along with a fabricating method involving patterning and releasing processes to create a gap between vibrating and sensing portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a traditional MEMS vibration sensor is mounted on the inner wall of the shell using adhesive, then the sensor can detect vibrations, but it occupies a large space which is not conducive to product miniaturization
Solution Approach 1:
The sensor is divided into multiple functional layers including a substrate layer, sensing layer, electrode layer, and protective layer. Each layer performs a specific function, allowing the sensor to maintain high sensitivity while reducing overall size through efficient spatial organization of components.
Solution Approach 2:
The patent implements a nested structure where the sensing layer is positioned within the substrate, electrodes are integrated within the sensing layer, and a protective layer encapsulates the entire sensing structure. This nested arrangement maximizes functional density while minimizing the sensor's footprint.
2Measurement precision
If a traditional MEMS vibration sensor is mounted on the inner wall of the shell using adhesive, then the sensor can be easily installed, but it exhibits poor sensitivity
Solution Approach 1:
The patent replaces the traditional mechanical adhesive mounting method with an integrated MEMS fabrication process. The sensor structure is formed using sequential deposition of layers (substrate, sensing material, electrodes, protective coating) followed by photolithographic patterning, eliminating the need for separate mounting steps and improving sensitivity through precise structural control.
Solution Approach 2:
The patent optimizes sensitivity by controlling critical parameters including the thickness of the sensing layer, the spacing between electrodes, and the mechanical properties of the substrate. These parameters are precisely controlled during fabrication to achieve high sensitivity while maintaining manufacturability through standard MEMS processing techniques.
3Measurement precision
If the sensing-portion is placed close to the vibrating-portion to improve sensitivity, then vibration detection is enhanced, but the structure becomes more complex
Solution Approach 1:
The patent merges the sensing portion and vibrating portion into a single integrated structure where the sensing layer is directly formed on the vibrating membrane. This integration eliminates the need for separate mounting mechanisms and complex alignment procedures, achieving high sensitivity through close proximity while simplifying the overall device structure.
Solution Approach 2:
The vibrating membrane serves multiple functions: it acts as both the vibrating element that responds to acoustic pressure and as the substrate for the sensing layer. This multi-functionality reduces structural complexity by eliminating the need for separate vibrating and sensing components, while maintaining high sensitivity through the direct coupling of the sensing layer to the vibrating membrane.
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 improves sensitivity and reduces size, enabling more effective vibration detection and amplification, suitable for applications in various vibration analysis devices.
Implementation Method 1
a MEMS vibration sensor (used to detect the vibration of the bones and tissues in the ear canal) is provided on the basis of a traditional MEMS microphone (used to detect the weaker airborne sound of higher speech frequency) to convert the sound waves into mechanical vibrations of different frequencies
Implementation Method 2
The sensing-portion is disposed on the vibrating-portion; and there is a gap between the sensing-portion and the vibrating-portion
Data Source
AI summary
A MEM vibration sensor includes a substrate and a sensing-device. The substrate includes a first supporting-portion and a cavity. The sensing-device includes a first sensing-unit, a second sensing-unit, a first metal pad and a second metal pad. The first sensing-unit includes a second supporting-portion and a vibrating-portion. The second supporting-portion is located on the first supporting-portion and is connected to the first supporting-portion via a first dielectric material. The vibrating-portion is located on the cavity, and is connected with the second supporting-portion through an elastic connecting-portion. The second sensing-unit is located on the first sensing-unit and includes a sensing-portion and a third supporting-portion. The sensing-portion is located on the vibrating-portion and has a gap with the vibrating-portion. The third supporting-portion is located on the second supporting-portion, is connected to the sensing-portion, and is connected to the second supporting-portion through a second dielectric material.