Stepper Flow Valve Control in Flow Cytometry for Consistent Particle Velocity

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Solution Overview

Problem

Existing flow cytometry systems face challenges in accurately controlling fluid flow velocity, leading to misrepresentation of cell or particle identities, and often rely on complex and unreliable control systems.

Innovation Solution

A flow cytometry system with dual laser devices and dual scatter channels, utilizing a stepper motor modulated flow control valve and a feedback control system to maintain constant fluid flow rates through a vacuum pump based on differential pressure, ensuring consistent particle velocity and reliable operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a complex fluid control system with multiple control devices is used, then flow control capability is improved, but system reliability deteriorates

Engineering Contradiction:
Improveflow control capabilityVSAvoidsystem reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent removes unnecessary control devices from the fluid control system, retaining only the essential components (flow cell, fluidic pathways, and basic flow control mechanisms). This extraction of non-essential elements simplifies the system while maintaining adequate flow control capability, thereby improving reliability by reducing potential failure points.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using multiple active control devices to manage fluid flow, the patent inverts the approach by using passive flow control through carefully designed fluidic pathways and pressure differential management. The system relies on the natural flow dynamics and minimal intervention, turning a complex active control problem into a simpler passive control solution that enhances reliability.

Inventive Principle:
Principle #13The other way round (Inversion)

2Device complexity

If fluid flow velocity is not properly controlled, then system simplicity is maintained, but measurement precision deteriorates

Engineering Contradiction:
Improvesystem simplicityVSAvoidcell or particle identification accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent controls fluid flow velocity by adjusting key parameters such as pressure differential across the flow cell and fluidic resistance in the pathways. By precisely managing these parameters, the system maintains appropriate flow velocity for accurate particle analysis without requiring complex control mechanisms, thus preserving system simplicity while ensuring measurement precision.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a balanced flow environment by equating the pressure potentials at critical points in the fluidic system. This equipotential approach ensures stable and uniform fluid flow through the flow cell, providing consistent particle velocities that enable accurate measurements while avoiding the need for complex active control systems.

Inventive Principle:
Principle #12Equipotentiality

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 stable and reliable fluid control, enabling accurate analysis of particles across varying conditions, minimizing pulse width variations and maintaining consistent particle velocities, thus improving measurement precision.

Implementation Method 1

a feedback control system to maintain constant fluid flow rates through a vacuum pump based on differential pressure

Methodology Applied
Scientific EffectPressure differential control: Pressure Gradient

Implementation Method 2

a stepper motor modulated flow control valve to control the proportion of sheath flow rate and sample flow rate

Methodology Applied
Scientific EffectStepper motor modulation: Linear Motor

Data Source

PatentEP3541536B1Flow cytometry systems with stepper flow control valve
Publication Date: 2025.10.22 CYTEK BIOSCI
  • EP3541536B1 patent drawingFigure 1
  • EP3541536B1 patent drawingFigure 2A~2B
  • EP3541536B1 patent drawingFigure 3A~3B

AI summary

A system, method, and apparatus are provided for flow cytometry. In one example, the flow cytometry system includes dual laser devices and dual scatter channels to measure velocity of particles in a core stream of sample fluid. The total flow rate of the sample fluid and the sheath fluid around the sample fluid is controlled, and thus held constant, by a feedback control system controlling a vacuum pump based on differential pressure across ends of a flow channel in the flow cell. A stepper flow control valves are disclosed that apply a physical fluid resistance to a flow of sheath fluid in the flow cytometer. The physical fluid resistance regulates a flow rate of the sheath fluid and thereby regulates a flow rate of sample fluid in the flow cytometer.