Flow Cytometer Drop Delay Calculation Using Imaging Sensors

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Solution Overview

Problem

Flow cytometers face inaccuracies in predicting droplets containing particles of interest due to perturbations in the flow stream, leading to imprecise cell sorting and contamination, especially when turbulence is caused by variability in particle size or drift in cytometer components.

Innovation Solution

The method involves determining the drop delay of a flow stream by obtaining and comparing different frequencies of drop perturbation, using imaging sensors and processors to capture and analyze images of the flow stream, allowing for automated adjustment of parameters like electrical charge timing and flow rate without the need for calibration particles or manual input.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional hydrodynamic estimation is used to predict droplet contents, then the system is simple to operate, but the prediction accuracy deteriorates due to flow stream perturbations and turbulence

Engineering Contradiction:
Improvedroplet prediction accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional hydrodynamic mechanical estimation with an optical measurement system using imaging sensors to directly observe and measure flow stream position and droplet characteristics, thereby achieving higher prediction accuracy without relying on simplified hydrodynamic models

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an imaging sensor as an intermediary device that captures images of the flow stream and droplets, allowing indirect measurement of droplet contents and flow position through image analysis rather than direct mechanical measurement

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If manual calibration and parameter adjustment are used, then the system requires less computational resources, but the time consumption and labor intensity increase

Engineering Contradiction:
Improvecell sorting speedVSAvoidcalibration time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The system performs automated self-calibration by using the imaging sensor to capture flow stream characteristics and automatically calculating drop delay and timing parameters, eliminating the need for manual calibration operations and enabling the system to adjust itself based on real-time observations

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent implements a feedback mechanism where images of the flow stream are continuously captured, analyzed to determine actual droplet positions and timing, and used to automatically adjust charging and deflection timing parameters, creating a closed-loop system that optimizes performance in real-time

Inventive Principle:
Principle #23Feedback

3Adaptability or versatility

If flow stream turbulence is present due to particle variability, then the system can handle diverse samples, but the droplet prediction reliability deteriorates

Engineering Contradiction:
Improvesample type flexibilityVSAvoiddroplet prediction reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces hydrodynamic modeling that assumes laminar flow with direct optical measurement of actual droplet positions and flow stream characteristics, allowing the system to accurately predict droplet contents even when turbulence and flow variations occur due to diverse particle sizes and sample types

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 approach enhances the predictability and accuracy of cell sorting by reducing turbulence-related errors, improving the precision and reliability of flow cytometry analyses by automatically determining optimal operating conditions for the flow cytometer.

Implementation Method 1

the flow cell is rapidly vibrated by an acoustic device, such as a piezoelectric transducer

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

rapidly vibrated by an acoustic device

Methodology Applied
Scientific EffectAcoustic vibration: Acoustic Radiation Pressure

Implementation Method 3

light from the irradiation source (e.g., laser) is scattered

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 4

The light can also excite components in the cell stream that have fluorescent properties, such as fluorescent markers

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 5

the flow stream is subjected to an electrical charge upstream from the deflection plate such that the first frequency and second frequency are determined from one or more captured images of the deflected flow stream

Methodology Applied
Scientific EffectElectrostatic deflection: Electrostatics

Data Source

PatentUS10302545B2Automated drop delay calculation
Publication Date: 2019.05.28 BECTON DICKINSON & CO
  • US10302545B2 patent drawing
  • US10302545B2 patent drawing
  • US10302545B2 patent drawing

AI summary

Aspects of the present disclosure include methods and systems for determining drop delay of a flow stream in a flow cytometer. Methods according to certain embodiments include obtaining a first frequency (f1) of drop perturbation of a flow stream subjected to an oscillating vibration, capturing one or more images of the flow stream in a detection field, obtaining a second frequency (f2) of drop perturbation of the flow stream based on one or more of the captured images and determining the drop delay of the flow stream based on the first frequency and the second frequency. Systems for practicing the subject methods having an imaging sensor for capturing one or more images of the flow stream and a processor configured to calculate drop delay using one or more of the captured images are also provided. Non-transitory computer readable storage mediums are also described.