Flow Cytometer Frequency Modulation for Accurate Particle Characterization

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Solution Overview

Problem

Existing flow cytometry techniques face challenges in accurately determining parameters of particles in a flow stream due to variations in light scattering and emission by biological samples, which affect the quantification and characterization of sample components.

Innovation Solution

Irradiating particles in a flow stream with a frequency-modulated beam of laser light, detecting scattered light with photodetectors, generating a frequency-encoded data signal, and synchronizing it with a reference frequency to determine particle parameters using systems and non-transitory computer readable storage media.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If frequency-modulated laser light is used to irradiate particles, then measurement precision is improved, but device complexity increases due to electro-optical modulators and synchronization systems

Engineering Contradiction:
Improveparticle parameter determination accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

An electro-optical modulator is introduced as an intermediary device between the laser source and the particle flow. This modulator imprints a frequency modulation onto the laser light at a reference frequency, enabling precise encoding of light intensity variations that correspond to particle parameters. The modulation acts as a mediator that transforms ordinary light into a precision measurement tool without requiring direct modification of the particle detection methodology

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

A synchronization system implements feedback by comparing the detected frequency-encoded signal with a reference frequency signal. The system uses this feedback to precisely determine particle parameters by correlating the modulated signal characteristics with known reference patterns, thereby improving measurement accuracy through continuous verification and adjustment

Inventive Principle:
Principle #23Feedback

2Reliability

If frequency encoding and synchronization are implemented, then reliability of particle characterization is improved, but difficulty of detecting and measuring increases

Engineering Contradiction:
Improveparticle characterization accuracyVSAvoidsignal processing complexity
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The system employs periodic frequency modulation at a reference frequency to encode particle information. By modulating the laser light at a known periodic rate and synchronizing detection with this reference frequency, the system transforms complex aperiodic particle scattering signals into regular, predictable frequency-encoded patterns that are easier to detect and measure reliably

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The invention changes the frequency parameter of the laser light as a function of particle properties. Instead of measuring only light intensity, the system encodes additional information in the frequency domain through modulation. This parameter transformation allows multiple particle characteristics to be measured simultaneously by analyzing different frequency components, improving reliability while organizing complex measurements into structured frequency domains

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

Enhances the accuracy of determining particle parameters by synchronizing frequency-encoded data signals with reference frequencies, allowing for precise characterization and sorting of particles in flow cytometry.

Implementation Method 1

generating the frequency modulated light by irradiating an electro-optical modulator with one or more lasers

Methodology Applied
Scientific EffectElectro-optic effect: Electro-Optic Effects

Implementation Method 2

In certain embodiments, the electro-optical modulator is a piezo optic modulator

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

In other embodiments, the electro-optical modulator is an acousto-optic modulator

Methodology Applied
Scientific EffectAcousto-optic effect: Acousto-optic Effect

Implementation Method 4

irradiating the electro-optical modulator with the laser through an input polarizer to generate a polarized frequency-modulated beam of laser light

Methodology Applied
Scientific EffectPolarization: Polarisation

Implementation Method 5

detecting scattered light from the particle with a photodetector

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 6

the scattered light is conveyed through a quarter wave plate to the scatter photodetector

Methodology Applied
Scientific EffectBirefringence: Birefringence

Implementation Method 7

synchronizing the frequency-encoded data signal with the reference frequency and determining one or more parameters of the particle based on the synchronized frequency-encoded data signal

Methodology Applied
Scientific EffectLock-in amplification: Homodyne Detection

Data Source

PatentEP4143536B1Methods for modulation and synchronous detection in a flow cytometer and systems for same
Publication Date: 2025.08.20 BECTON DICKINSON & CO
  • EP4143536B1 patent drawingFigure 1A
  • EP4143536B1 patent drawingFigure 1B
  • EP4143536B1 patent drawingFigure 2A

AI summary

Methods for determining a parameter of a particle in a flow stream (e.g., in a particle analyzer of a flow cytometer) from scattered light are described. Methods according to certain embodiments include irradiating a particle in a flow stream with a frequency-modulated beam of laser light modulated at a reference frequency, detecting scattered light from the particle with a photodetector, generating a frequency-encoded data signal from the detected scattered light, synchronizing the frequency-encoded data signal with the reference frequency and determining one or more parameters of the particle based on the synchronized frequency-encoded data signal. Systems and non-transitory computer readable storage medium with instructions for practicing the subject methods are also provided.