Expanded Polyethylene Acoustic Membrane for Immersion Durability
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Solution Overview
Problem
There is an ongoing need for improved acoustic membranes that provide low acoustic loss and mechanical protection in immersion applications while avoiding performance degradation over time, particularly in devices such as cellular phones, laptops, and tablets.
Innovation Solution
The use of a polyethylene membrane with specific properties, including a thickness of 0.5 μm to 14 μm, surface area per volume of 39×10^6/m to 70×10^6/m, geometric mean tensile modulus of 250 to 750 MPa, and porosity of 50% to 95%, which allows for efficient sound transmission and mechanical protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyethylene membrane is used for acoustic devices, then sound transmission is enabled, but mechanical protection in immersion applications is compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling the membrane's physical parameters including thickness (0.5-14 μm), porosity (50-95%), tensile modulus (250-750 MPa), and surface area per volume (39-70 ×10^6/m). These parameter optimizations enable the membrane to achieve both acoustic transmission and mechanical protection in immersion environments
Solution Approach 2:
The patent employs composite material structures by combining polyethylene material with specific physical properties and potential coatings or laminations. The composite approach allows the membrane to simultaneously provide acoustic transparency, mechanical strength, and protection against water and contaminants
2Loss of energy
If membrane porosity is increased to improve sound transmission, then acoustic loss is reduced, but mechanical strength and protection are compromised
Solution Approach 1:
The patent resolves this contradiction through parameter changes by optimizing porosity within a specific range (50-95%) while simultaneously adjusting other parameters such as thickness (0.5-14 μm) and tensile modulus (250-750 MPa). This multi-parameter optimization allows the membrane to maintain both low acoustic loss and adequate mechanical strength
Solution Approach 2:
The patent applies local quality by creating non-uniform pore distributions within the membrane structure. Different regions of the membrane can have varying porosity, with higher porosity areas providing acoustic transmission and lower porosity areas providing mechanical reinforcement, thereby achieving both goals simultaneously
3Loss of energy
If membrane thickness is reduced to improve acoustic transmission, then sound propagation is enhanced, but mechanical protection and durability are compromised
Solution Approach 1:
The patent applies parameter changes by optimizing thickness within a narrow range (0.5-14 μm) while compensating with adjustments in other parameters such as tensile modulus (250-750 MPa) and surface area per volume (39-70 ×10^6/m). This allows the membrane to remain thin for acoustic transmission while maintaining sufficient durability
Solution Approach 2:
The patent employs composite material structures that combine thin polyethylene layers with potential reinforcements or coatings. This composite approach enables the membrane to achieve the required thinness for acoustic transmission while gaining enhanced durability and resistance to degradation over time
4Strength
If tensile modulus is increased to improve mechanical protection, then strength is enhanced, but acoustic transmission is reduced
Solution Approach 1:
The patent resolves this contradiction through coordinated parameter changes by optimizing tensile modulus within a specific range (250-750 MPa) while simultaneously adjusting porosity (50-95%), thickness (0.5-14 μm), and surface area per volume (39-70 ×10^6/m). This multi-parameter optimization enables the membrane to achieve both mechanical protection and acoustic transmission
Solution Approach 2:
The patent applies local quality by creating anisotropic structures where the tensile modulus varies in different directions. The membrane can have higher tensile modulus in one direction for mechanical protection while maintaining lower stiffness in another direction for acoustic transmission, achieving both goals simultaneously
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 polyethylene membrane maintains consistent acoustic performance and mechanical integrity over time, reducing plastic deformation and ensuring reliable sound transmission in harsh environments.
Implementation Method 1
the polyethylene membrane has a porosity of 50% to 95%
Implementation Method 2
a % recovery at 1 hour after 1 bar open hole challenge is at least 69%
Data Source
AI summary
An assembly includes an acoustic device. The acoustic device can include a polyethylene membrane. The polyethylene membrane can have first direction and a second direction, the second direction being orthogonal to the first direction. The polyethylene membrane can have a surface area per volume of at least 39×106/m. The polyethylene membrane can have a geometric mean tensile modulus of 250 to 750 MPa. The polyethylene membrane can have a maximum tensile modulus in the first direction of 440 to 915 MPa. The polyethylene membrane can have a maximum tensile modulus in the second direction of 275 to 515 MPa. The polyethylene membrane can be an expanded polyethylene membrane.