Labyrinth Microfluidic Channel for Rare Cell Separation
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Solution Overview
Problem
Current methods for detecting rare cells, such as circulating tumor cells, face challenges with low yield, purity, and throughput due to clogging and pressure issues in size-based separation techniques, and require pre-fixation which affects efficiency and sample processing capacity.
Innovation Solution
A microfluidic device with a labyrinth channel structure that utilizes inertial migration and Dean flow forces to separate rare cells from other cells by flowing the fluid sample through channels with multiple segments and corners, allowing for high throughput and high purity separation without pre-fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If size-based separation techniques using pores etched in membranes are used to separate CTCs from red blood cells, then CTCs can be trapped on the membrane, but the pores become clogged and pressure drops due to collection of cells on the membranes
Solution Approach 1:
The device segments the separation process into multiple functional zones: inertial focus zone where cells are separated by size, Dean flow zone where cells are directed to different outlets, and collection zones. This segmentation allows continuous processing without clogging by distributing cell collection across multiple pathways rather than concentrating it at a single membrane filter.
Solution Approach 2:
The patent replaces the mechanical filtration system (pores in membranes) with a fluid dynamics-based separation system using inertial forces and Dean flows. Cells are separated based on their size and flow characteristics rather than being physically trapped by pores, eliminating the clogging problem while maintaining separation efficiency.
2Reliability
If pre-fixation of cells is performed to prevent them from squeezing through pores, then cell retention improves, but processing speed decreases and non-specific cell retention increases
Solution Approach 1:
The patent replaces the need for pre-fixation with a physical separation mechanism based on inertial forces and Dean flows. Cells are separated in their native, unfixed state using hydrodynamic forces that exploit size differences and flow patterns, eliminating the trade-off between retention efficiency and processing speed.
Solution Approach 2:
The patent changes the separation parameters from chemical fixation to physical flow characteristics. By controlling flow rate, channel geometry, and fluid dynamics parameters, the system achieves reliable cell retention without requiring pre-fixation, thereby maintaining high processing speeds.
3Measurement precision
If immunoaffinity capture methods are used to isolate CTCs, then specific detection is achieved, but processing speeds are low compared to size-based methods
Solution Approach 1:
The device segments the separation process into distinct zones: inertial focus for size-based separation, Dean flow for directional sorting, and collection zones. This multi-stage segmentation achieves both high specificity (through controlled flow paths) and high throughput (through continuous processing and parallel collection channels).
Solution Approach 2:
The patent uses hydraulic forces (inertial forces and Dean flows) to achieve cell separation, combining the throughput advantages of size-based methods with the specificity of controlled flow dynamics. The system uses fluid flow patterns to selectively direct different cell types to different outlets, achieving both speed 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
The microfluidic device achieves efficient separation and collection of rare cells with high recovery and purity, enabling accurate detection and analysis of rare cells in small fluid samples without the need for pre-processing, thus improving diagnostic capabilities.
Implementation Method 1
The presence of the plurality of corners induces separation of the rare cells from the other cells in the fluid sample as the rare cells move to a first equilibrium position within the at least one channel when a ratio of inertial lift forces (Fz) and Dean flow (FD) of the fluid sample is from 2 to 10
Implementation Method 2
The presence of the plurality of corners induces separation of the rare cells from the other cells in the fluid sample as the rare cells move to a first equilibrium position within the at least one channel when a ratio of inertial lift forces (Fz) and Dean flow (FD) of the fluid sample is from 2 to 10
Data Source
AI summary
A microfluidic device for detecting rare cells in a fluid sample comprises the rare cell and other cells. The microfluidic device comprises an inlet for receiving the fluid sample, a labyrinth channel structure in fluid communication with the inlet, and an outlet in fluid communication with the labyrinth channel structure for collecting the rare cells separated from the other cells in the fluid sample. The labyrinth channel structure comprises at least one channel through which the fluid sample flows. The at least one channel has a plurality of segments and a plurality of corners with each corner defined between adjacent segments. The presence of the plurality of corners induces separation of the rare cells from the other cells in the fluid sample as the rare cells move to a first equilibrium position within the at least one channel when a ratio of inertial lift forces (FZ) and Dean flow (FD) of the fluid sample is from 2 to 10.