Microfabricated Filter with Non-Uniform Substrate
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Solution Overview
Problem
Conventional microfabricated filters face challenges such as brittleness, performance breakdown, and increased pressure gradients as filter dimensions decrease, necessitating improved filtration devices with reduced pore sizes and enhanced manufacturing efficiency.
Innovation Solution
Microfabricated filtration devices with a planar membrane section and a support section featuring a substrate with thick portions and recesses, along with an additional dielectric layer, are developed. These devices include pores with widths less than 100 nm and a substrate with thin portions between thick portions, allowing for improved diffusive transport and reduced manufacturing queue times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If filter pore dimensions are decreased to improve filtration efficiency, then filtration performance is improved, but pressure gradients increase above usable thresholds
Solution Approach 1:
The substrate is designed with non-uniform thickness, featuring thick portions for structural support and thin portions (10-100 μm) directly beneath the membrane pores. This local variation in thickness reduces the diffusive path length specifically where needed (under the pores) while maintaining overall structural integrity, thereby reducing pressure gradients without compromising filtration efficiency.
Solution Approach 2:
The invention introduces a vertical dimension variation in the substrate thickness to address the pressure gradient issue. By creating thin portions that extend upward toward the membrane, the design effectively reduces the vertical transport distance for filtered materials, alleviating the pressure buildup that would otherwise occur with uniform thin substrates.
2Manufacturing precision
If filter dimensioning is decreased to produce fine mesh filters, then filtration precision is improved, but manufacturing issues such as brittleness increase
Solution Approach 1:
The substrate employs a non-uniform thickness profile with thick portions providing structural support and thin portions enabling fine filtration. This local differentiation allows the device to achieve high filtration precision through the thin membrane regions while the thick substrate portions maintain structural integrity and resist brittleness.
Solution Approach 2:
The device combines a thin membrane section (for fine filtration) with a thicker substrate (for structural support) to create a composite structure. This composite design integrates materials or regions with different thicknesses to simultaneously achieve both high filtration precision and adequate mechanical strength.
3Productivity
If membrane thickness is reduced to improve diffusive transport, then transport efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The substrate is segmented into distinct thick and thin portions, with the thin portions (10-100 μm) strategically located beneath the membrane pores to enhance diffusive transport. This segmentation allows the thin regions to provide rapid transport pathways while the thick regions maintain manufacturability and structural support, avoiding the need for an entirely ultra-thin substrate that would be difficult to manufacture.
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 solution provides enhanced filtration efficiency with reduced diffusive resistance, allowing for improved transport characteristics and reduced membrane surface requirements, while also streamlining fluid flow and refresh rates across the filtration device.
Implementation Method 1
improved diffusive transport
Data Source
AI summary
The present technology provides micro fabricated filtration devices, methods of making such devices, and uses for microfabricated filtration devices. The devices may allow diffusion to occur between two fluids with improved transport resistance characteristics as compared to conventional filtration devices. The devices may include a compound structure that includes a porous membrane overlying a support structure. The support structure may define a cavity and a plurality of recesses formed in a way that can allow modified convective flow of a first fluid to provide improved diffusive transport between the first fluid and a second fluid through the membrane.