Flow Cytometry Fluorescence Measurement Using Modulated Lasers
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Solution Overview
Problem
Flow cytometry systems face challenges in accurately measuring overlapping fluorescence emissions from multiple excitation sources due to spatial filtering limitations, which reduce sensitivity and increase complexity, especially when dealing with multiple lasers, leading to inter-beam crosstalk and limited scalability.
Innovation Solution
The system employs modulated excitation lasers with different frequencies, combining these beams into a single collinear excitation beam, allowing a single detector to measure fluorescent emissions and using signal processing to distinguish and correct for emissions from each laser source, eliminating the need for spatial filtering and reducing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spatial filtering is used to separate emissions from multiple excitation sources, then measurement precision is improved, but sensitivity is reduced and device complexity increases
Solution Approach 1:
The patent applies periodic modulation to each excitation laser source at distinct frequencies. This temporal periodicity allows the system to encode each excitation source's emission signal with its unique frequency signature, enabling separation of overlapping emissions through frequency-domain analysis without requiring complex spatial filtering optics.
Solution Approach 2:
The patent changes the frequency parameter of each excitation source to create distinguishable signals. By modulating each laser at a different frequency and using Fourier transform analysis on the combined emission signal, the system can resolve and quantify emissions from multiple sources simultaneously, avoiding the need for multiple detectors or complex spatial arrangement.
2Measurement precision
If multiple detectors are used to measure emissions from multiple lasers, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes a single detector perform the function of multiple detectors by using frequency-based signal separation. The single detector captures the combined emission signal from all excitation sources, and the signal processing system uses Fourier transform to decompose this single signal into contributions from each modulated excitation source, achieving multi-source measurement capability with a single detection device.
Solution Approach 2:
The patent introduces signal processing (Fourier transform) as an intermediary between the detector and the measurement result. This intermediary process separates the mixed emission signals in the frequency domain, allowing accurate quantification of each fluorophore's emission without requiring physical separation or multiple detectors.
3Measurement precision
If spatial filtering is used to eliminate inter-beam crosstalk, then measurement precision is improved, but sensitivity is reduced
Solution Approach 1:
By modulating each excitation laser at a unique frequency, the system creates temporally distinct emission signals. This allows the full intensity of each excitation beam to be used for fluorescence excitation without spatial filtering, while the frequency-encoded signals are separated during data acquisition, maintaining both sensitivity and precision.
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 sensitivity, simplifies setup, and scales well with multiple lasers, enabling simultaneous, quantitative measurements without the need for multiple detectors or off-axis optics, effectively addressing the limitations of spatial filtering in flow cytometry.
Implementation Method 1
The fluorescent probes bound to a cell emit fluorescent light as the cell passes through a tightly focused, high intensity, light beam (typically a laser beam)
Implementation Method 2
beam combining optics adapted to receive said first and second modulated excitation beams and produce a combined modulated excitation beam
Data Source
AI summary
A system and method for the measurement of multiple fluorescence emissions in a flow cytometry system is disclosed where each excitation light source is modulated with a different frequency. A single detector is used to collect the fluorescent emissions excited by all light sources, and the emissions are segregated using Fourier Transform techniques. Systems and methods for the correction of inter-beam coincidence are also disclosed.