Microfluidic Milk Classification Using Real-Time BRET Sensing

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Solution Overview

Problem

Existing methods for detecting analytes in samples, such as milk or cheese, face challenges with high costs, limited sensitivity, slow reaction times, and sensor drift, making real-time monitoring difficult and requiring surface regeneration.

Innovation Solution

A microfluidic method using a sensor molecule with a chemiluminescent donor and acceptor domain within a specific Förster distance, allowing real-time detection of analytes through binding analytes and substrates, and electro-optical sensing to modify the BRET ratio, enhancing sensitivity and reducing sensor drift.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If surface-based sensing techniques (SPR) are used, then real-time monitoring is enabled, but surface regeneration is required causing downtime

Engineering Contradiction:
Improvereal-time monitoring capabilityVSAvoiddowntime for surface regeneration
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent extracts the sensing function from a surface-based system and transfers it to freely diffusing sensor molecules in solution. The sensor molecules are not attached to any surface but instead float freely in the microfluidic channel, allowing continuous monitoring without regeneration downtime. This is achieved by using fluorescently labeled sensor molecules that bind to analytes in solution phase.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical surface regeneration process with an optical detection system. Instead of physically regenerating a sensor surface, the system uses fluorescence resonance energy transfer (FRET) between freely diffusing sensor molecules and analytes, detected optically without mechanical intervention. This substitution eliminates the need for surface regeneration and associated downtime.

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

2Measurement precision

If conventional detection equipment is used, then BRET can be detected, but the equipment is sophisticated and costly

Engineering Contradiction:
ImproveBRET detection capabilityVSAvoidsophisticated detection equipment
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent creates a simplified optical copy of the BRET phenomenon by using fluorescently labeled sensor molecules where the fluorescent label acts as the acceptor. This allows detection using standard fluorescence microscopy equipment rather than specialized BRET detection systems. The fluorescent label copies the energy transfer function in a more accessible format.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent changes the detection parameter from measuring bioluminescence resonance energy transfer directly to measuring fluorescence intensity changes. By converting the BRET signal into a fluorescence signal that can be detected by standard equipment, the system maintains measurement precision while reducing device complexity and cost.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If microfluidic technologies are used, then reagent consumption is reduced and reaction rate is fast, but integration of multiple components increases cost per chip

Engineering Contradiction:
Improvefast reaction rateVSAvoidintegration of multiple components
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent designs the microfluidic chip to perform multiple functions using a single integrated structure. The chip includes reservoirs, mixing chambers, and detection zones all in one device, eliminating the need for separate equipment for sample preparation, mixing, and detection. This multi-functionality reduces the overall system cost while maintaining fast reaction rates.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges multiple discrete components (sensor molecules, substrates, mixing mechanisms, and detection systems) into a single integrated microfluidic chip. The sensor molecules and substrates are combined in the same chamber where mixing and detection occur simultaneously, reducing the number of separate components and lowering per-chip costs.

Inventive Principle:
Principle #5Merging (Combining)

4Quantity of substance

If electronic noses and tongues are used, then analyte detection is performed, but sensor selectivity and sensitivity are poor

Engineering Contradiction:
Improveanalyte detection capabilityVSAvoidsensor selectivity and sensitivity
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent uses different fluorescently labeled sensor molecules with specific binding properties for different analytes. Each sensor molecule has localized specificity for particular targets (e.g., lactose, proteins, bacteria), allowing highly selective detection within the complex milk matrix. This local quality of sensor specificity overcomes the poor selectivity of electronic nose sensors.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs a composite sensing system combining multiple fluorescently labeled sensor molecules, each with different binding specificities. This composite approach allows simultaneous detection of multiple analytes with high selectivity and sensitivity, overcoming the limitations of single-type sensors in electronic noses and tongues.

Inventive Principle:
Principle #40Composite materials

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 method achieves rapid, sensitive, and real-time detection of analytes with improved signal-to-noise ratio, reducing downtime and costs, and enabling precise concentration coding.

Implementation Method 1

a chemiluminescent donor domain and an acceptor domain

Methodology Applied
Scientific EffectChemiluminescence: Chemiluminescence

Implementation Method 2

RET is a ratiometric technique which can eliminate data variability caused by fluctuations in light output due to variations in assay volume, assay conditions and signal decay across different wells in a plate

Methodology Applied
Scientific EffectFörster resonance energy transfer:

Implementation Method 3

a domain that binds one or more analytes

Methodology Applied
Scientific EffectMolecular binding:

Data Source

PatentEP4180799B1Method of classifying milk
Publication Date: 2025.12.24 PPB TECHNOLOGY PTY LTD
  • EP4180799B1 patent drawingFigure 1
  • EP4180799B1 patent drawingFigure 2A~2B
  • EP4180799B1 patent drawingFigure 3~4(c)

AI summary

The present invention relates to methods and systems for detecting one or more analytes in a sample and/or for classifying a sample. In particular, the present invention relates to methods and systems which can be used to detect the analytes in real time and which rely on flowing through a microfluidic device one or more types of sensor molecule each comprising a domain that binds one or more analytes, a chemiluminescent donor domain and an acceptor domain, wherein the separation and relative orientation of the chemiluminescent donor domain and the acceptor domain, in the presence and/or absence of analyte is within ± 50% of the Forster distance.