Microfluidic Vortex Trapping for Rare Cell Enrichment
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Solution Overview
Problem
Current methods for isolating and analyzing circulating tumor cells (CTCs) from bodily fluids are inefficient due to their low frequency and the complexity of biofluids, requiring expensive antibodies and manual, time-consuming processes that are limited by the scarcity of target cells and the heterogeneity of tumor markers.
Innovation Solution
A label-free microfluidic device with expansion regions that trap target cells based on size, allowing for enrichment and analysis without labels, using flow rates to detach boundary layers and create vortices for purification, followed by downstream analysis of cell count, size, and morphology using high-speed cameras or laser interrogation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional flow cytometry or Coulter Counter methods are used for cell enumeration, then automated cell counting and size measurement are achieved, but the methods have limited specificity and cannot accurately detect rare cells at low frequencies (1-500 CTCs/mL) due to high background noise from billions of normal blood cells
Solution Approach 1:
The invention segments the cell analysis process into two distinct stages: (1) label-free enrichment of rare cells using microfluidic devices with deterministic lateral displacement structures that separate cells based on size and deformability, and (2) subsequent analysis of the enriched population using flow cytometry or other analysis methods. This segmentation allows the enrichment step to concentrate rare cells from a complex background, thereby improving detection accuracy while enabling the use of simpler, more cost-effective analysis equipment.
Solution Approach 2:
The invention performs preliminary enrichment of rare cells before analysis using microfluidic devices that exploit physical properties (size, deformability) to concentrate target cells. This preliminary action removes the need for complex labeling and manual manipulation steps, directly improving detection sensitivity for rare cells at low frequencies while reducing overall system complexity and cost.
2Measurement precision
If immunostaining methods with antibodies are used to identify and analyze rare cells, then classification accuracy is improved, but the process becomes time-consuming, expensive, and requires manual manipulation by trained technicians
Solution Approach 1:
The invention replaces the mechanical and chemical processes of immunostaining (manual manipulation, antibody binding, fluorescence microscopy) with a label-free microfluidic enrichment system that uses physical principles (deterministic lateral displacement, vortex trapping) to separate and concentrate rare cells. This substitution eliminates the need for antibodies and manual steps, dramatically reducing analysis time and cost while maintaining high classification accuracy through subsequent automated analysis of the enriched population.
Solution Approach 2:
The microfluidic enrichment device performs self-service separation of rare cells based on their intrinsic physical properties (size, deformability) without requiring external labels or manual intervention. Cells automatically follow different flow paths or become trapped in vortex regions based on their physical characteristics, enabling automated, rapid enrichment that eliminates time-consuming manual manipulation steps.
3Manufacturing precision
If immunostaining protocols with multiple wash, labeling, and incubation steps are used, then purity of CTC samples is improved, but the native state of cells is altered and further assays are limited
Solution Approach 1:
The invention replaces chemical fixation, permeabilization, and antibody binding steps with label-free physical enrichment using microfluidic devices. This substitution preserves the native state and viability of rare cells, enabling subsequent live cell assays (culture, drug testing, molecular analysis) while maintaining high sample purity through deterministic lateral displacement and vortex trapping mechanisms.
Solution Approach 2:
The invention extracts rare cells from complex biofluids using label-free physical enrichment based on size and deformability differences, without introducing antibodies or chemicals that would alter cell state. This extraction method preserves cell viability and native characteristics, enabling further assays while achieving high purity enrichment.
4Ease of manufacture
If manual hemocytometer methods are used for cell counting, then low-cost analysis is achieved, but the process is time-consuming and lacks automation
Solution Approach 1:
The invention performs preliminary enrichment of rare cells using automated microfluidic devices, concentrating target cells from large sample volumes into smaller, manageable populations. This preliminary automated action enables subsequent analysis using simpler, lower-cost equipment (such as standard flow cytometers or even automated imaging systems) to achieve high throughput, combining the cost-effectiveness of simpler methods with the productivity of automation.
Solution Approach 2:
The invention segments the analysis process into automated enrichment (high throughput, low cost) followed by analysis of enriched samples. This segmentation allows the use of cost-effective analysis methods on concentrated samples, achieving both low cost and high productivity by processing many samples through the enrichment step and analyzing only the enriched rare cell populations.
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
Enables low-cost, automated, and efficient enrichment and analysis of rare cells, reducing the need for antibodies and allowing for live cell collection for further testing, improving the detection of malignancies and guiding clinical decision-making.
Implementation Method 1
The expansion regions provide an abrupt increase in the width of the microfluidic channel that, at or above certain flow rates, create a detached boundary layer that causes the formation of vortices within each expansion regions. The vortices created within the expansion regions trap a target population or subpopulation of un-labeled cells
Implementation Method 2
The expansion regions provide an abrupt increase in the width of the microfluidic channel that, at or above certain flow rates, create a detached boundary layer that causes the formation of vortices within each expansion regions
Implementation Method 3
The released enriched target cells can then be selectively analyzed downstream from the expansion regions by reducing or completely eliminating flow through the microfluidic device
Implementation Method 4
Analysis may also be performed using a laser interrogation that detects the diffraction or the scattering of laser light from incident cells in a flow using a detector such as a photomultiplier tube (PMT)
Implementation Method 5
Another analysis technique that may be integrated includes the use of electrodes in a downstream flow path to measure changes in electrical impedance corresponding to cell volume and conductivity
Data Source
AI summary
A system and method for the label-free analysis of cells includes a purification device configured to receive a heterogeneous population of cells, the purification device temporarily trapping therein a subpopulation of cells from the heterogeneous population of cells and a cell analysis device positioned downstream of the purification device and configured to measure one or more cellular parameters including cell count, measured cell size, and/or cell morphology. In an alternative embodiment, the subpopulation of cells is analyzed while they are trapped within the purification device.