UV Lithography Microfilters for Precision Cell Isolation
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Solution Overview
Problem
Current methods for fabricating high-aspect-ratio precision nanopores and nanopillars in polymer films are limited by low aspect ratios, fragility, and random pore distributions, which hinder efficient isolation and detection of rare cells from biological samples, particularly circulating tumor cells.
Innovation Solution
The use of ultra-violet (UV) lithography and x-ray lithography to pattern and etch predetermined pore sizes, distributions, and shapes in polymer films, enabling the fabrication of precision microfilters with high aspect ratios and controlled pore arrangements, suitable for large-area production and medical applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If track etch method is used to fabricate nanopores, then manufacturing capability is improved, but pore distribution becomes random and aspect ratio is limited
Solution Approach 1:
The patent replaces the mechanical track etch process with a photochemical lithography process using UV or X-ray exposure through masks. This substitution enables precise control of pore size, shape, and distribution through optical patterning rather than random mechanical drilling, while maintaining high manufacturing capability through batch processing of multiple filters simultaneously.
Solution Approach 2:
The patent changes the fabrication parameters by using different lithography methods (UV vs X-ray), varying mask designs, and adjusting exposure conditions to achieve predetermined pore sizes from 1-100 micrometers. This allows precise control over pore diameter, depth, and spatial distribution, resolving the contradiction between manufacturing efficiency and precision.
2Manufacturing precision
If high aspect ratio nanopores are fabricated, then filtration precision is improved, but filter fragility increases
Solution Approach 1:
The patent addresses fragility by transitioning from single-layer thin membranes to multi-layer stacked structures. Each layer contains an array of pores, and the stacking provides mechanical reinforcement while maintaining the high aspect ratio precision of individual pores. This dimensional approach allows filters to achieve both high precision and structural strength.
Solution Approach 2:
The patent uses composite filter structures combining multiple polymer layers with different mechanical properties. The layered composite design provides both the precise pore geometry needed for high-aspect-ratio filtration and the structural integrity to prevent fragility, resolving the contradiction between precision and strength.
3Reliability
If multiple layers of filters are used to avoid analyte loss, then capture efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple filter functions into a single integrated multi-layer structure where each layer contributes to the overall capture efficiency. The layers are designed with complementary pore patterns that work together to prevent analyte loss, achieving high reliability without requiring separate filter assemblies or complex handling procedures.
Solution Approach 2:
The patent segments the filtration function across multiple layers, with each layer optimized for specific pore sizes or capture targets. This segmentation allows systematic design of capture efficiency while maintaining modular simplicity, where each layer can be independently fabricated and then assembled into the complete filter device.
4Productivity
If large area production is achieved, then manufacturing throughput is improved, but maintaining precision across the area becomes difficult
Solution Approach 1:
The patent uses mask-based lithography where a master mask pattern is copied across the entire filter area through UV or X-ray exposure. This copying process ensures identical pore patterns are replicated over large areas with high precision, maintaining uniformity while enabling batch production of multiple filters simultaneously, thus resolving the contradiction between throughput and precision.
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 approach allows for efficient enrichment and detection of rare cells, such as circulating tumor cells, with high precision and throughput, facilitating downstream analyses and therapeutic applications, while providing a cost-effective and bio-compatible solution for various medical and industrial filtration needs.
Implementation Method 1
The use of ultra-violet (UV) lithography and x-ray lithography to pattern and etch predetermined pore sizes, distributions, and shapes in polymer films
Implementation Method 2
optical interference lithography using ultra-violet radiation
Data Source
AI summary
Micro- and nanofilters with precision pore sizes and pore layout have applications in many fields including capturing circulating tumor cells and fetal cells in blood, water treatment, pathogen detection in water, etc. Methods to fabricate micro- and nanofilters not using track etching or reactive ion etching are provided, allowing easy fabrication of single layer or stack of films simultaneously, and/or stack of films on rolls. Microfilter can be made using one or more layers of material. Invention enables mass production of microfilters with lithographic quality at low cost. Isolation, enumeration and characterization of circulating tumor cells using microfilters provides (i) guides to cancer treatment selection and personalize dosage, (ii) low cost monitoring for treatment response, disease progression and recurrence, (iii) assessment of pharmacodynamic effects, (iv) information on mechanisms of resistance to therapy, and (v) cancer staging. Microfabrication methods are also applicable to fabrication of any free standing patterned polymeric films.