Diaphragm Flow Control for Stable Sheath Pressure in Cytometers
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Solution Overview
Problem
Flow cytometers face challenges in maintaining consistent sheath flow rates and pressures, which are crucial for efficient particle sorting, due to variations in temperature, equipment operation, and fluid characteristics, leading to inefficiencies in sorting operations.
Innovation Solution
A fluid handling system that regulates fluid flow by using a control fluid and a working fluid, with a flexible diaphragm separating two volumes, where the diaphragm's position is monitored to adjust the flow rate and pressure of the working fluid, ensuring stable and invariant flow parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a peristaltic pump is used to supply working fluid, then the flow rate can be controlled, but pulse variations in flow rate occur
Solution Approach 1:
A compliant tube is introduced as an intermediary element between the peristaltic pump and the flow regulator. This tube acts as a fluid capacitor that absorbs and dampens the pulsatile flow generated by the pump, converting it into a more continuous flow while maintaining the controlled flow rate capability.
Solution Approach 2:
The system transitions from a static flow delivery approach to a dynamic one by using a compliant tube that can expand and contract in response to pressure variations. This dynamic behavior allows the tube to actively compensate for pump-induced flow pulsations, stabilizing the overall flow delivery.
2Productivity
If flow rate is increased to improve sorting efficiency, then productivity increases, but flow parameter variations worsen
Solution Approach 1:
A pressure sensor provides real-time feedback on the pressure within the sheath fluid line, and this information is fed to a controller that adjusts the peristaltic pump speed accordingly. This closed-loop feedback system maintains stable flow parameters even at higher flow rates, enabling improved sorting efficiency without sacrificing flow stability.
Solution Approach 2:
The system dynamically changes the operational parameters of the peristaltic pump based on real-time conditions. By adjusting pump speed in response to pressure feedback, the system can operate at higher flow rates for improved productivity while maintaining stable flow parameters through continuous parameter optimization.
3Adaptability or versatility
If environmental conditions vary (temperature, voltage), then operational flexibility is maintained, but flow rate and pressure stability deteriorate
Solution Approach 1:
The pressure sensor and controller form a feedback loop that continuously monitors and adjusts the system in response to environmental variations. When temperature, voltage, or other environmental conditions change, the feedback mechanism detects the resulting pressure deviations and automatically adjusts pump operation to maintain stable flow and pressure, enabling environmental adaptability without sacrificing stability.
Solution Approach 2:
The system is designed to self-correct for environmental variations through its feedback mechanism. Rather than requiring external intervention or manual adjustment, the system automatically compensates for temperature, voltage, and other environmental changes, maintaining stable flow parameters through self-regulating control.
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 system provides a consistent and stable flow of fluid to the flow cytometer, reducing variations in flow parameters and enhancing the instrument's operational efficiency by maintaining precise control over fluid flow rates and pressures.
Implementation Method 1
supplying a first quantity of a substantially incompressible working fluid having a first pulse peak-to-peak value from a peristaltic pump
Implementation Method 2
a flexible barrier, also referred to as a diaphragm, located between the control fluid volume containing the control fluid and the working fluid volume containing the working fluid
Implementation Method 3
The second pulse peak-to-peak value may be less than the first pulse peak-to-peak value
Data Source
AI summary
A fluid handling system for supplying a working fluid to a fluid flow instrument is disclosed. The system includes a controller configured to receive sensor signals indicative of a deformation of a flexible barrier located between a control fluid volume containing a control fluid and a working fluid volume containing the working fluid. Based on the sensor signals, the controller may send signals to control the operation of a working fluid flow generator in order to regulate or control the fluid characteristic of the working fluid being provided to the fluid flow instrument.