Microfluidic Device Using Centrifugal Forces for CTC Sorting
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Solution Overview
Problem
Current microfluidic devices are inadequate for selectively sorting multi-cellular clusters of circulating tumor cells (CTCs) due to their reliance on phenotype-based targeting methods and size filtration, which fail to distinguish between single cells and cell clusters, leading to inaccurate enrichment and detection.
Innovation Solution
A microfluidic device with a rotatable substrate and a segmented bias rail that uses centrifugal forces to sort particles of varying sizes into discrete bins, allowing for the isolation and characterization of single cells, medium clusters, and large multi-cell events, minimizing cell packing errors and enabling accurate scoring of cluster sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phenotype-based targeting methods are used to isolate CTCs, then cell enrichment is achieved, but the method requires prior knowledge of cell phenotype and cannot distinguish between single cells and cell clusters
Solution Approach 1:
The patent changes the separation parameter from phenotype-based recognition to size-based physical separation. By rotating the microfluidic device, centrifugal forces are generated that deflect cells laterally according to their size, enabling discrimination between single cells and multi-cellular clusters without requiring phenotype knowledge.
2Measurement precision
If size filtration using porous filters or track-etched membranes is used, then CTC enrichment based on increased cell size is achieved, but the system cannot distinguish between single cells and cell clusters that strike the membrane at the same point
Solution Approach 1:
The patent introduces a lateral dimension to the separation process by rotating the device. Instead of vertical filtration through membranes, cells are deflected laterally by centrifugal forces into different collection zones based on size, adding a spatial dimension that enables differentiation between single cells and clusters.
Solution Approach 2:
The patent segments the collection area into multiple discrete zones (first collection zone for single cells, second collection zone for clusters) separated by a partition. This segmentation allows simultaneous collection and differentiation of different cell size populations without the ambiguity of membrane filtration.
3Adaptability or versatility
If a rotatable substrate with centrifugal force is used to bias fluid movement, then particle sorting based on size is enabled, but device complexity increases
Solution Approach 1:
The rotating substrate serves multiple functions: it generates centrifugal forces for particle separation, enables fluid flow through the channels, and allows adjustment of separation parameters by varying rotation speed. This multi-functionality reduces the need for additional components.
Solution Approach 2:
The patent employs a dynamic rotation mechanism that allows the separation parameters to be adjusted by changing rotation speed. This dynamic control enables the same device to sort different particle sizes and types without requiring multiple fixed configurations.
4Measurement precision
If single-cell resolution capture traps are used, then single CTC identification is achieved, but multi-cellular cluster detection is not suitable
Solution Approach 1:
The patent segments the collection system into distinct zones: a first collection zone for single cells and a second collection zone for multi-cellular clusters. The partition between zones is configured with specific dimensions that allow size-based separation, enabling simultaneous detection and differentiation of both single cells and clusters.
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 isolates and characterizes CTC clusters, providing a quantifiable metric for cluster sizes and distribution, which is essential for clinical diagnostics and biomedical research, while avoiding the limitations of existing methods that require phenotype knowledge or size-based filtration.
Implementation Method 1
uses an induced centrifugal field resultant from a rotation of the substrate to bias fluid movement within the channels of the chip
Implementation Method 2
A microfluidic device with a rotatable substrate and a segmented bias rail that uses centrifugal forces to sort particles of varying sizes into discrete bins
Data Source
AI summary
Microfluidic devices that are configured to use centrifugal forces to bias particles into one or more capture regions based on their individual sizes are described.