Integrated Particle and Light Filter for MEMS Microphones
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Solution Overview
Problem
Compact consumer electronics devices, such as laptops and smartphones, face challenges with microphone performance due to the susceptibility of miniaturized microphones to particle, water, and light ingress, which can lead to failure.
Innovation Solution
A MEMS microphone with an integrated particle filter and light filter, featuring a multi-layer structure with interconnected pathways to prevent particle ingress and a light barrier material to block UV, visible, or IR light, is developed using batch processing MEMS operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If microphones are made compact to fit modern consumer electronics, then device size is reduced, but susceptibility to particle, water and light ingress increases
Solution Approach 1:
The filter is divided into multiple material layers (first material layer, second material layer, third material layer) with different properties. Each layer serves specific functions: the first layer with axial pathways allows acoustic transmission, the second layer provides light blocking, and the third layer offers additional particle filtration. This segmentation enables the filter to simultaneously achieve compact size and protection against multiple harmful factors.
Solution Approach 2:
The filter employs composite material construction with at least three different material layers having different acoustic and optical properties. The combination of materials with varying densities, porosity, and light absorption characteristics creates a multi-functional barrier that protects the microphone while maintaining acoustic performance in a compact form factor.
2Reliability
If a particle filter with multiple material layers is added to the microphone, then particle ingress is prevented, but device complexity increases
Solution Approach 1:
The particle filter and light filter functions are merged into a single integrated structure. The multiple material layers are formed as one unified component that simultaneously filters particles and blocks light, eliminating the need for separate filter assemblies and reducing overall device complexity despite the multi-layer construction.
Solution Approach 2:
The multi-layer filter structure serves multiple functions simultaneously: acoustic signal transmission, particle filtration, and light blocking. This multi-functionality is achieved within a single integrated component that reduces the overall complexity of the microphone assembly by combining what would traditionally require separate elements.
3Reliability
If a light filter is added to block UV, visible or IR light, then light ingress is prevented, but manufacturing complexity increases
Solution Approach 1:
The light-blocking properties are incorporated into the filter structure during the initial manufacturing process. The second material layer with light-absorbing or light-blocking properties is formed as part of the filter assembly before the microphone is finalized, preventing light ingress from the outset and eliminating the need for additional post-assembly modifications.
Solution Approach 2:
The light filter functionality is merged with the particle filter structure. The second material layer serves dual purposes: providing mechanical support as part of the filter assembly and simultaneously blocking light across UV, visible, and IR spectra. This integration simplifies manufacturing by reducing the total number of separate components that would need to be assembled.
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 integrated filter effectively prevents particle and light ingress, enhancing the reliability and audio performance of compact microphones without increasing device size or requiring additional manufacturing steps.
Implementation Method 1
a particle filter that prevents particles from reaching the compliant member by forming a tortuous network of pathways that traps particles
Implementation Method 2
a light filter that blocks light within an ultraviolet (UV), visible or infrared (IR) wavelength range from entering the device
Implementation Method 3
The light filter may be reflective or opaque to light in at least one of an infrared (IR), visible or ultraviolet (UV) light wavelength range
Data Source
AI summary
A micro-electro-mechanical system (MEMS) transducer including an enclosure defining an interior space and having an acoustic port formed through at least one side of the enclosure. The transducer further including a compliant member positioned within the interior space and acoustically coupled to the acoustic port, the compliant member being configured to vibrate in response to an acoustic input. A back plate is further positioned within the interior space, the back plate being positioned along one side of the compliant member in a fixed position. A filter is positioned between the compliant member and the acoustic port, and the filter includes a plurality of axially oriented pathways and a plurality of laterally oriented pathways which are acoustically interconnected and dimensioned to prevent passage of a particle from the acoustic port to the compliant member.