Microfluidic Droplet Sorting with 45-Degree Detection
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Solution Overview
Problem
Current microfluidic technologies face challenges in reliably co-encapsulating two different cell types at the single-cell level and performing quantitative antibody binding assays, due to non-deterministic cell encapsulation and issues with fluorescently labelled objects floating out of the focal plane or laser spot.
Innovation Solution
A microfluidic system with a novel sorting device and labelling approach that allows for the selection of droplets with desired occupancy, including two different cell types, and a method for normalizing fluorescence signals to quantify binding independently of the object's position within the droplet, using a detection channel and sorting channel tilted at 45° and additional oil inlets to control droplet trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-deterministic cell encapsulation is used, then the process is simple, but the cell occupancy in each droplet cannot be controlled tightly
Solution Approach 1:
The patent applies preliminary action by pre-labeling cells with fluorescent markers before encapsulation. This allows the system to determine cell occupancy in advance and make selective sorting decisions, transforming a post-encapsulation selection problem into a pre-planned sorting operation that ensures precise control of cell occupancy in each droplet.
2Measurement precision
If fluorescently labelled objects are used for detection, then the detection is sensitive, but the objects can float out of the focal plane or out of the centre of the laser spot
Solution Approach 1:
The patent implements feedback by using the fluorescent signal from the labeled object as both a detection marker and a positioning reference. The system continuously monitors the fluorescent signal intensity and uses this feedback to determine whether the object remains within the focal plane and laser spot center, enabling real-time correction and maintaining quantitative analysis reliability throughout the measurement process.
Solution Approach 2:
The fluorescently labeled object serves as an intermediary that connects detection and positioning functions. By attaching fluorescent markers to the object of interest, the system can simultaneously detect the object's presence and track its position, using the same fluorescent signal as a mediator for both measurement and spatial localization, thereby ensuring reliable quantitative analysis even when objects move.
3Adaptability or versatility
If two different cell types are co-encapsulated, then the screening capability is enhanced, but the reliable co-encapsulation at single-cell level has not been demonstrated
Solution Approach 1:
The patent applies segmentation by differentiating the two cell types with distinct fluorescent labels, allowing the system to individually identify and count each cell type within droplets. This segmentation of identification enables precise control of co-encapsulation, ensuring that each droplet contains exactly one cell of each type by providing clear visual distinction and counting capability for sorting decisions.
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 precise co-encapsulation of two cell types and quantitative analysis of antibody binding, enhancing drug screening and antibody discovery processes by ensuring accurate sorting and measurement of binding interactions regardless of the object's position.
Implementation Method 1
measuring the intensity of a signal peak of the first detectable label, measuring an intensity of a signal peak of the second detectable label
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
The present invention relates to the field of microfluidics and in particular to methods for detecting microfluidic droplets and particles within droplets, as well as sorting the droplets. These methods allow for quantifying properties and activities of the particles within the droplets. For this purpose, the invention provides microfluidic droplets comprising suitably labelled particles. The invention also provides microfluidic devices and systems having properties which make them particularly suitable for use in the methods of the invention.