Microfluidic Cell Sorting via Impedance-Triggered Ejection Pauses
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Solution Overview
Problem
Current microfluidic technologies face challenges in accurately sorting and dispensing single cells into reservoirs for applications like monoclonal antibody production, requiring efficient separation and imaging of cells within fluid samples to ensure high throughput and low cross-contamination.
Innovation Solution
A microfluidic device equipped with impedance sensors and an imaging apparatus that controls fluid ejection based on impedance changes, allowing for the separation and imaging of cells, and uses a learning-based process to classify and dispense cells into specific reservoirs based on type and presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluid is continuously ejected from the microfluidic device, then throughput is maximized, but cell separation accuracy deteriorates due to inability to pause for imaging and classification
Solution Approach 1:
The system implements periodic action by alternating between continuous fluid ejection modes (for high throughput) and paused modes (for imaging and classification). The controller receives impedance sensor signals and periodically pauses fluid ejection to capture images and classify cells, then resumes ejection to maintain throughput. This periodic interruption allows accurate cell separation while maintaining overall productivity.
2Measurement precision
If fluid ejection is paused for imaging and classification, then cell separation accuracy is improved, but productivity decreases
Solution Approach 1:
The system employs feedback control where impedance sensors continuously monitor the fluid stream for cell presence and characteristics. When cells are detected, the controller receives this feedback and temporarily pauses fluid ejection to capture images and perform classification. After processing, the controller resumes ejection, maintaining the balance between accuracy and productivity through real-time feedback-driven decisions.
3Adaptability or versatility
If multiple cells are present in the fluid sample, then sorting complexity increases, but the system can handle diverse cell types through impedance-based detection and imaging
Solution Approach 1:
The system segments the cell sorting process into distinct functional stages: (1) impedance-based detection and counting of cells in the fluid stream, (2) temporary pause of fluid ejection, (3) imaging of individual cells, (4) classification based on impedance signals and image analysis, and (5) targeted dispensing into appropriate reservoirs. This segmentation allows the system to handle diverse cell types systematically while managing complexity through modular processing steps.
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 sorting and dispensing of cells, reducing cross-contamination and increasing production efficiency, while providing verification images for regulatory compliance and quality assurance in monoclonal antibody production.
Implementation Method 1
A controller receives an impedance signal from an impedance sensor disposed in the channel. The controller executes imaging instructions in response to a change in the impedance signal.
Data Source
AI summary
A non-limiting example method for control of fluid ejection from a microfluidic device includes firing a microfluidic ejector of a microfluidic device to expel a fluid from a channel of the microfluidic device. In response to detecting an instance of signal change from an impedance sensor disposed in the channel, the method includes controlling fluid ejection from the microfluidic ejector and capturing an image of the channel with an imaging apparatus. Using the captured image, a determination is made as to whether passage of a cell into the channel is associated with the instance of signal change from the impedance sensor. Based on the determination, the microfluidic ejector may fire to dispense the fluid from the channel into a reservoir.