Sample Injection Needle Positioning for Stable Flow Cytometry Core Streams

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Solution Overview

Problem

Conventional flow cytometer systems suffer from fluid perturbations and eddies in the flow stream due to inadequate control of cell travel speed, leading to a breakdown of the core stream and core stream instability.

Innovation Solution

The development of flow cytometers with improved sample injection needles that maintain an intact core stream under varying flow conditions, featuring specific configurations and positions to ensure laminar flow and reduce perturbations by a magnitude or more, including a sample injection needle with a passage, a flow cell cone, and precise positioning relative to sheath fluid introduction ports and interrogation points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional sample injection mechanisms are used, then sample delivery is achieved, but fluid perturbations and eddies are created in the flow stream

Engineering Contradiction:

Improvesample deliveryVSAvoidflow stream stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The sample injection needle is pre-positioned at an optimized distance from the interrogation point before sample delivery begins. This preliminary positioning ensures that the sample enters the flow cell at the correct location to maintain laminar flow and prevent eddies from forming, thereby achieving stable flow stream composition while enabling effective sample delivery

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the critical parameter of injection needle positioning distance. By optimizing this parameter to a specific range from the interrogation point, the system transforms the flow conditions from turbulent with eddies to laminar and stable, while still achieving effective sample delivery into the core stream

Inventive Principle:

Principle #35Parameter changes

2Productivity

If sample injection needle is positioned closer to interrogation point, then sample delivery efficiency improves, but core stream breakdown occurs

Engineering Contradiction:

Improvesample delivery efficiencyVSAvoidcore stream integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention identifies and optimizes the positioning distance parameter of the sample injection needle relative to the interrogation point. By setting this parameter within a specific range, the system achieves the optimal balance where sample delivery efficiency is maximized while core stream integrity is maintained, preventing both stream breakdown and excessive delivery delays

Inventive Principle:

Principle #35Parameter changes

3Productivity

If flow rate is increased to improve analysis speed, then productivity improves, but flow stream perturbations increase

Engineering Contradiction:

Improveanalysis speedVSAvoidflow stream stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The system pre-conditions the flow by ensuring the sample injection needle is correctly positioned before high-speed analysis begins. This preliminary setup allows the system to maintain laminar flow patterns even at increased flow rates, enabling faster analysis without sacrificing flow stream stability or introducing harmful perturbations

Inventive Principle:

Principle #10Preliminary action

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 improved sample injection needles achieve a significant reduction in flow stream and core stream perturbations by 20% or more, maintaining a stable core stream under diverse flow conditions, enhancing the accuracy and reliability of particle analysis.

Implementation Method 1

a sample injection needle having a passage running therethrough for delivering sample fluid from a sample injection line at a proximal end to the flow cell at a distal end to generate the core stream

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 2

a flow cell for transporting particles in a core stream of a flow stream from a proximal end to a distal end

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 3

a light source configured to illuminate the flow cell at an interrogation point

Methodology Applied

Scientific EffectLight: Light

Implementation Method 4

flow cytometers include a vacuum configured to draw fluid through the flow cell

Methodology Applied

Scientific EffectVacuum: Vacuum

Data Source

PatentUS12546797B2Flow cytometers including sample injection needles, and methods of use thereof

Publication Date: 2026.02.10 BECTON DICKINSON & CO

AI summary

Flow cytometers having sample injection needles are provided. The subject flow cytometers include a flow cell for transporting particles in a core stream of a flow stream from a proximal end to a distal end, and a sample injection needle having a passage running therethrough for delivering sample fluid from a sample injection line at a proximal end to the flow cell at a distal end to generate the core stream. Flow cells of interest include a flow cell cone at the proximal end, and sample injection needles of interest are configured and positioned to maintain an intact core stream under flow conditions that vary by a magnitude or more. Methods of assembling the subject flow cytometers and methods of analyzing a sample using the subject flow cytometers are also provided.