Elevated MEMS Microphone Mesh Screen for Contaminant Protection
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Solution Overview
Problem
Existing MEMS microphones face performance degradation and contaminant ingress issues due to previous protection methods that introduce unacceptable noise and decrease signal-to-noise ratio.
Innovation Solution
The implementation of a mesh screen ingress protection element, constructed from polyamide film with small openings, positioned under the MEMS device and extending beyond the port hole, creating multiple acoustic pathways to reduce noise and prevent contaminant entry while maintaining acoustic sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional protection methods are used to prevent contaminant ingress, then reliability is improved, but signal-to-noise ratio deteriorates due to unacceptable noise levels
Solution Approach 1:
The patent employs a porous acoustic absorption material positioned between the port and the MEMS diaphragm. This material has a porous structure that allows acoustic waves to pass through while trapping contaminants. The pores enable sound transmission but the complex internal structure of the porous material captures and retains contaminant particles, thus protecting the MEMS components without significantly degrading the acoustic signal and maintaining signal-to-noise ratio.
Solution Approach 2:
The acoustic absorption material serves as an intermediary element between the external environment and the MEMS diaphragm. It mediates the interaction between sound waves and contaminants by allowing sound to pass through while blocking contaminants. This intermediary layer protects the sensitive MEMS components from direct exposure to contaminants while maintaining acoustic performance.
2Reliability
If protection structures are added to prevent contaminant ingress, then reliability is improved, but device complexity increases
Solution Approach 1:
The acoustic absorption material performs multiple functions simultaneously: it absorbs excess acoustic energy, traps contaminants, and maintains acoustic impedance matching. This multi-functionality reduces the need for separate protection components, thereby limiting the increase in device complexity while still providing reliable contaminant protection.
Solution Approach 2:
The patent optimizes parameters of the acoustic absorption material such as porosity, flow resistance, and thickness to achieve effective contaminant protection with minimal impact on acoustic performance. By carefully controlling these parameters, the protection mechanism is achieved without requiring complex structural modifications to the microphone device.
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 solution effectively prevents contaminant ingress without degrading microphone performance, enhancing signal-to-noise ratio and being easily adaptable to existing microphone configurations.
Implementation Method 1
a mesh screen ingress protection element constructed from polyamide film with small openings
Implementation Method 2
sound energy traverses through the port, moves the diaphragm and creates a changing potential of the back plate
Data Source
AI summary
A micro electro mechanical system (MEMS) microphone includes a base including a port extending through the base, a shim assembly, an ingress protection element, and a MEMS device. The shim assembly is disposed on the base and over the port. The shim assembly has a plurality of walls that form a hollow interior cavity. The shim assembly also has a top surface and a bottom surface coupled to the base. The ingress protection element extends over and is coupled to the top of the shim assembly to enclose the cavity of the shim assembly. The shim assembly elevates the ingress protection element above the base and is effective to prevent the passage of contaminants there through. The MEMS device includes a diaphragm and a back plate and is disposed over the ingress protection element.