Multi-Pump Sheath Flow Control for Low-Pulsatility Cytometry
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Solution Overview
Problem
Flow cytometers face challenges in maintaining stable sheath flow rates for both high and low flow rates, particularly with viscous fluids, due to limitations in current pump and fluidic channel systems, leading to pulsatility and reduced accuracy in particle analysis.
Innovation Solution
The use of multiple gear pumps operating in different modes to provide a stable flow with minimal pulsatility across a wide dynamic range of flow rates, combined with pressure sensors for differential pressure measurements to ensure precise control and adjustment of flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If syringe pumps are used for volumetric delivery, then robustness with respect to fluid temperature and viscosity is improved, but pulsatility increases and dynamic range is limited
Solution Approach 1:
The patent combines multiple syringe pumps operating in parallel to deliver sheath fluid. By merging the output of multiple pumps, the system achieves both robustness to fluid property variations and reduced pulsatility through averaging effects, while extending the dynamic range beyond what a single pump could provide.
Solution Approach 2:
The system uses multiple syringe pumps with overlapping stroke cycles to ensure continuous, smooth fluid delivery. The pumps are synchronized so that when one pump is at the end of its stroke, another is mid-stroke, eliminating gaps and reducing overall pulsatility while maintaining continuous volumetric delivery.
2Ease of operation
If peristaltic pumps are used, then ease of operation is improved, but pulsatility increases significantly
Solution Approach 1:
Multiple peristaltic pumps are operated in parallel to combine their pulsatile outputs. The superposition of multiple slightly offset pulsation cycles results in a smoother composite flow with reduced overall pulsatility, while retaining the ease of operation characteristics of peristaltic pumping.
Solution Approach 2:
The system exploits the periodic nature of peristaltic pump operation by carefully coordinating the stroke cycles of multiple pumps. By adjusting the phase relationships between pumps, the system creates a composite periodic flow that averages out individual pulsations, achieving smoother flow while maintaining the periodic driving mechanism.
3Stability of the object's composition
If pressure reservoirs and regulators are used, then flow rate stability is improved, but adaptability to different flow rates is reduced
Solution Approach 1:
The system transitions from static pressure reservoirs to dynamic syringe pump delivery, where the pump speed can be continuously adjusted. This allows the system to adapt to different flow rate requirements while maintaining stability through precise volumetric control, achieving both stability and adaptability across a wide dynamic range.
Solution Approach 2:
The system changes the controlling parameter from fixed pressure head to variable pump speed. By adjusting the rotation speed of the syringe pump motor, the system can deliver a wide range of flow rates while maintaining volumetric precision, thus achieving both stability and adaptability that pressure reservoirs alone cannot provide.
4Productivity
If high flow rates are used, then productivity is improved, but measurement precision of particle transit time deteriorates
Solution Approach 1:
The system uses continuous, smooth syringe pump delivery to minimize flow disturbances and pulsations. This continuous stable flow ensures that particles travel at consistent velocities even at high flow rates, maintaining precise transit time measurements while achieving high throughput.
Solution Approach 2:
The system incorporates flow sensors and control systems that monitor and adjust pump operation in real-time. This feedback mechanism ensures that even at high flow rates, the actual delivered flow matches the target flow, maintaining measurement precision while maximizing productivity.
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
This configuration achieves a stable and precise flow rate with minimal pulsatility, enabling reliable operation across a wide range of applications, including high and low flow rates, and is suitable for both aqueous and oil-based fluids, reducing errors in particle analysis and extending the dynamic range of flow cytometry applications.
Implementation Method 1
The use of multiple gear pumps operating in different modes to provide a stable flow with minimal pulsatility across a wide dynamic range of flow rates
Implementation Method 2
combined with pressure sensors for differential pressure measurements to ensure precise control and adjustment of flow rates
Implementation Method 3
Acquiring precise quantitative data in flow cytometry embodiments depend on stable flow rate for sheath flow that deliver particles with consistent velocity and position through the detection region
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An embodiment of a system with a minute measure of pulsatility in a flow of a fluid is described that comprises a first pump configured to flow the fluid to a junction at a first flow rate that comprises a measure of pulsatility; and a second pump configured to flow a portion of the fluid from the junction at a second flow rate that is less than the first flow rate to produce a flow of the fluid at a third flow rate from the junction with a minute measure of pulsatility.