Microfluidic Obstacle Arrays for Rare-Cell Enrichment
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Solution Overview
Problem
Existing cell separation techniques, such as flow cytometry and cell sorting, require large and expensive equipment, large sample volumes, and skilled operators, and often fail to enrich samples sufficiently for analyzing rare components, leading to unacceptable losses and inefficiencies.
Innovation Solution
Devices featuring arrays of obstacles that deterministically deflect particles based on hydrodynamic size, using structures that divide fluid flow unequally to direct particles into major or minor fluxes, allowing for enrichment and alteration of samples, including microfluidic channels and methods for preferential lysis of specific cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow cytometry and cell sorting methods are used, then cell separation is achieved, but the equipment is large and expensive, requiring large sample volumes and skilled operators
Solution Approach 1:
The device segments the flow cytometry function into discrete microfabricated components: microchannels, obstacle arrays, and collection chambers. This segmentation enables the complex separation function to be achieved through simple geometric structures rather than expensive commercial instruments
Solution Approach 2:
The invention creates a simplified copy of flow cytometry functionality using microfabricated obstacle arrays that replicate the cell deflection and separation principles of commercial flow cytometers, but in a miniaturized, low-cost format suitable for point-of-care applications
2Measurement precision
If conventional cell sorting techniques are employed, then cell separation is performed, but sample volume requirements are large
Solution Approach 1:
The invention transitions from macro-scale flow cytometry to micro-scale dimensions, using microchannels with characteristic dimensions of 10-100 micrometers. This dimensional change enables sufficient cell separation with much smaller sample volumes, making the technique suitable for precious or limited clinical samples
3Measurement precision
If electrostatic deflection, centrifugation, FACS, or MACS methods are used, then cell separation is achieved, but rare components cannot be enriched sufficiently
Solution Approach 1:
The device creates local quality variations through obstacle arrays with specifically designed gap sizes and patterns. Cells of different sizes experience different local flow conditions as they pass through gaps of varying dimensions, enabling precise size-based separation and enrichment of rare cell populations with high resolution
4Measurement precision
If conventional separation techniques are used, then cell separation is performed, but unacceptable losses occur through inefficient separation or degradation
Solution Approach 1:
The invention replaces harsh mechanical separation forces (centrifugation, electrostatic deflection) with gentle microfluidic flow dynamics. Cells are separated based on passive hydrodynamic interactions with obstacle arrays, eliminating mechanical stress that causes cell degradation and minimizing losses of rare and fragile 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
Enriches samples by increasing the relative population of target cells by up to 1,000,000-fold, reduces mechanical stress on cells, and allows for efficient separation and alteration of rare cells with high precision and low equipment costs.
Implementation Method 1
structures that deterministically deflect particles, in a fluid, having a hydrodynamic size above a critical size in a direction not parallel to the average direction of flow of the fluid in the structure
Implementation Method 2
particles having a hydrodynamic size above a critical size... the particles are directed into the major flux
Data Source
AI summary
The invention features devices and methods for the deterministic separation of particles. Exemplary methods include the enrichment of a sample in a desired particle or the alteration of a desired particle in the device. The devices and methods are advantageously employed to enrich for rare cells, e.g., fetal cells, present in a sample, e.g., maternal blood and rare cell components, e.g., fetal cell nuclei. The invention further provides a method for preferentially lysing cells of interest in a sample, e.g., to extract clinical information from a cellular component, e.g., a nucleus, of the cells of interest. In general, the method employs differential lysis between the cells of interest and other cells (e.g., other nucleated cells) in the sample.