Microfluidic Device for CTC Separation Using Inertial and Dean Drag Forces
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Solution Overview
Problem
Current methods for cell analysis, such as flow cytometry and magnetic-bead column selection, are cumbersome, costly, and often damage cells, and are not portable, making them unsuitable for efficient isolation and classification of rare cells like circulating tumor cells (CTCs) which are crucial for cancer prognosis and monitoring.
Innovation Solution
A microfluidic device with a conduit having alternating contraction and expansion regions, utilizing inertial and Dean drag forces to separate cells based on size, allowing for efficient isolation of CTCs without labeling or damaging them, and incorporating a flow resistive element to maintain balanced flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cell analysis methods (flow cytometry, magnetic-bead column selection) are used, then cell separation can be achieved, but the procedures become cumbersome, costly, and cells are damaged
Solution Approach 1:
The device segments the cell separation process into distinct functional zones within a single microfluidic chip: inertial focusing region, Dean drag separation region, and collection channels. This segmentation allows different separation mechanisms to work in sequence, achieving high purity isolation of rare cells without complex external equipment or multiple processing steps
Solution Approach 2:
The invention replaces complex mechanical systems (flow cytometers, magnetic bead columns) with a passive microfluidic system that uses inertial and Dean drag forces. No active mechanical manipulation, external magnets, or complex actuators are needed—the fluid dynamics itself performs the separation function, dramatically simplifying the device while maintaining reliability
2Reliability
If traditional cell analysis methods are used, then cell separation can be achieved, but additional costs and sample loss occur due to exogenous labeling requirements
Solution Approach 1:
The microfluidic device performs separation using the cells' own physical properties (size, density, deformability) and the fluid's inherent inertial and secondary flow characteristics. No external labels, tags, or modifying reagents are needed—the system uses what is already present, eliminating sample loss from labeling procedures while achieving high separation purity
Solution Approach 2:
The device exploits natural variations in cell parameters (size, density, mechanical properties) to achieve separation. By carefully controlling flow rate and channel geometry, the system amplifies these natural parameter differences into distinct separation outcomes, eliminating the need for exogenous labeling while maintaining high purity isolation
3Productivity
If traditional cell analysis methods are used, then cell analysis can be performed, but the devices are not portable and require advanced preparation
Solution Approach 1:
The invention merges sample preparation, separation, and analysis functions into a single integrated microfluidic chip. The chip receives crude samples directly and performs all necessary processing internally through its designed flow paths and separation zones, eliminating the need for separate preparation steps and external equipment, thereby enabling portability while maintaining high isolation efficiency
Solution Approach 2:
The microfluidic device is designed as a universal platform that can handle various sample types (blood, tissue dissociates, body fluids) and separate different cell types by adjusting flow parameters and channel geometry. This multi-functionality allows a single portable device to replace multiple specialized instruments, improving both productivity and ease of operation across different applications
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 device effectively separates CTCs from other blood components with high purity and viability, enabling accurate enumeration and monitoring of CTCs, improving upon existing methods by reducing costs and enhancing portability.
Implementation Method 1
utilizing inertial and Dean drag forces to separate cells based on size
Implementation Method 2
utilizing inertial and Dean drag forces to separate cells based on size
Implementation Method 3
incorporating a flow resistive element to maintain balanced flow
Data Source
AI summary
Devices for separating constituents (e.g., cells) in a fluid sample are provided. The device includes a microfluidic conduit configured to carry a flow of a fluid sample and includes two or more separation elements, each separation element including a first region and a second region, where the first region has a cross-sectional area less than a cross-sectional area of the second region. The device also includes a flow resistive element in fluid communication with the microfluidic conduit in a region between two adjacent separation elements. Also provided are methods of using the devices, as well as systems and kits that include the devices. The devices, systems, methods and kits find use in a variety of different applications, including diagnostic assays.