Pump-Vacuum Fluid Management for Flow Cytometer Accuracy

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Solution Overview

Problem

Existing flow cytometers face challenges in efficiently managing fluid flow rates and maintaining consistent fluid resistance, leading to variations in particle analysis accuracy due to external environmental exposure and pressure fluctuations.

Innovation Solution

A fluid management system that integrates a pump modulated sheath fluid subsystem and a vacuum modulated waste fluid subsystem, utilizing positive displacement pumps, pulsation dampers, and pressure transducers to maintain constant fluid resistance and control flow rates, ensuring closed system operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional open fluid management systems are used in flow cytometers, then the system structure is simpler, but particle analysis accuracy varies due to external environmental exposure and pressure fluctuations

Engineering Contradiction:
Improveparticle analysis accuracyVSAvoidfluid management system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a closed fluid management system that isolates the fluidic pathways from the external environment, creating a controlled inert environment. This prevents environmental fluctuations (temperature, pressure, contamination) from affecting particle analysis accuracy, directly resolving the contradiction between measurement precision and device complexity by prioritizing a stable measurement environment.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

Solution Approach 2:

The patent incorporates pressure transducers and flow sensors that continuously monitor fluid pressure and flow rate, with feedback control mechanisms that actively adjust pump speeds and vacuum levels. This feedback system maintains constant fluid resistance and stable hydrodynamic focusing conditions, improving particle analysis accuracy while managing system complexity through automated control.

Inventive Principle:
Principle #23Feedback

2Productivity

If pump modulated sheath fluid subsystem and vacuum modulated waste fluid subsystem are integrated, then fluid flow rates are precisely controlled, but system complexity increases

Engineering Contradiction:
Improvefluid flow control precisionVSAvoidsubsystem integration complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent divides the fluid management system into distinct segmented subsystems: a pump-modulated sheath fluid subsystem for precise sheath flow control, and a vacuum-modulated waste fluid subsystem for controlled waste removal. Each subsystem operates independently with dedicated control mechanisms, allowing precise fluid flow management while organizing complexity into manageable modular components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent utilizes pneumatic principles by integrating a vacuum system that applies negative pressure to control waste fluid removal and assist in maintaining fluid flow rates. This pneumatic control mechanism, combined with hydraulic pump modulation, enables precise flow rate control through pressure differential management, resolving the contradiction between productivity and device complexity.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Stability of the object's composition

If constant fluid resistance is maintained through active control, then particle velocity consistency improves, but energy consumption increases

Engineering Contradiction:
Improveparticle velocity consistencyVSAvoidenergy consumption
Core Design Contradiction:
Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The patent designs the fluid management system to self-regulate fluid resistance through the inherent characteristics of the pump and vacuum system interactions. The system automatically balances sheath fluid delivery and waste removal to maintain constant fluid resistance without requiring continuous active intervention, reducing energy consumption while preserving particle velocity consistency.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent dynamically adjusts operational parameters (pump speed, vacuum level) to maintain constant fluid resistance under varying conditions. By changing these parameters adaptively rather than maintaining fixed high-energy settings, the system achieves stable particle velocity while optimizing energy consumption through parameter optimization.

Inventive Principle:
Principle #35Parameter changes

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 precise control over fluid flow rates, maintaining consistent particle velocity and reducing external exposure, thereby enhancing the accuracy and reliability of particle analysis in flow cytometers.

Implementation Method 1

utilizing positive displacement pumps

Methodology Applied
Scientific EffectPositive displacement:

Implementation Method 2

vacuum modulated waste fluid subsystem

Methodology Applied
Scientific EffectVacuum: Vacuum

Implementation Method 3

pulsation dampers

Methodology Applied
Scientific EffectPulsation damping: Damping

Implementation Method 4

pressure transducers

Methodology Applied
Scientific EffectPressure sensing:

Implementation Method 5

the particle-containing sample fluid is surrounded by a particle-free sheath fluid that forms an annular flow coaxial with the sample fluid as is passes through the detection region, thereby creating a hydrodynamically focused flow

Methodology Applied
Scientific EffectHydrodynamic focusing:

Data Source

PatentEP3837528B1Flowrate and vacuum controlled fluid management system for a flow type particle analyzer
Publication Date: 2025.09.17 BECTON DICKINSON & CO
  • EP3837528B1 patent drawingFigure 1
  • EP3837528B1 patent drawingFigure 2

AI summary

Flow rate and vacuum controlled fluid management systems for flow type particle analyzers, such as flow cytometers, are provided. Aspects of the fluid management systems include a pump modulated sheath fluid subsystem and a vacuum modulated waste fluid subsystem. Also provided are methods of using flow type particle analyzers having fluid management systems of the invention, e.g., in particle analysis applications.