Fountain Flow Cytometer Background Light Reduction
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Solution Overview
Problem
Conventional Fountain Flow Cytometry (FFC) systems face limitations in detection sensitivity due to high background light intensity, which affects the signal-to-noise ratio and dynamic range, primarily caused by Raman scattering, fluorescence from the flow cell and tubing, and ambient light leakage.
Innovation Solution
The implementation of techniques to reduce background light intensity, including constraining the interrogated volume using a light-absorbing reagent and a bend in the flow cell channel, and selecting excitation and emission filters to minimize Raman scattering, while focusing illumination tightly onto the focal plane to limit illuminated volume and reduce scattered light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Fountain Flow Cytometry is used to detect particles, then the system can operate with simple flow cell design, but the background light intensity is high which reduces signal-to-noise ratio and detection sensitivity
Solution Approach 1:
The flow cell channel is divided into multiple segments with different functions: an illumination section for light input, a focal plane for particle imaging, and a collection section for flow output. This segmentation allows each section to be optimized for its specific function while reducing overall background light intensity through strategic placement of optical elements and flow dynamics control.
Solution Approach 2:
The patent introduces a vertical dimension to the flow cell design by creating a three-dimensional illumination pattern that focuses light tightly onto the focal plane. This dimensional approach separates the illumination volume from the detection plane, reducing out-of-focus background light while maintaining effective particle excitation.
2Measurement precision
If illumination is focused tightly onto the focal plane to reduce interrogated volume, then background light from Raman scattering is reduced, but the illuminated volume is limited which may affect particle detection efficiency
Solution Approach 1:
The system maintains continuous particle detection efficiency by optimizing flow rate and illumination timing. The focused illumination continuously excites particles as they pass through the focal plane, and the flow system ensures continuous particle supply, maintaining high detection efficiency despite the reduced interrogated volume.
Solution Approach 2:
The patent optimizes detection efficiency by adjusting parameters such as illumination intensity, exposure time, and flow rate. These parameter changes compensate for the reduced interrogated volume by increasing the probability of particle detection within the focused illumination region through enhanced signal intensity and optimized sampling frequency.
3Measurement precision
If a bend is added to the flow cell channel to constrain interrogated volume, then background noise is reduced, but the flow path becomes more complex which may affect particle flow stability
Solution Approach 1:
The bend is introduced only in specific regions of the flow cell where it serves to redirect flow and constrain the interrogated volume, while other regions maintain straight, stable flow paths. This localized application of geometric complexity minimizes disruption to overall flow stability while achieving background noise reduction in the critical detection region.
4Measurement precision
If light-absorbing reagent is added to constrain interrogated volume, then signal-to-noise ratio is enhanced, but the sample preparation becomes more complex and may interfere with particle staining
Solution Approach 1:
The light-absorbing reagent acts as an intermediary substance that selectively absorbs scattered light and Raman radiation without interfering with the fluorescent staining of particles. This intermediary approach allows background noise reduction while maintaining particle detectability through the use of spectrally distinct optical agents.
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
These methods significantly enhance the signal-to-noise ratio and dynamic range by reducing background noise, allowing for improved detection sensitivity and accuracy in particle enumeration and identification.
Implementation Method 1
constraining an interrogated volume of a fountain flow cytometer by adding a light absorbing reagent to a measured sample
Implementation Method 2
constraining an interrogated volume of a fountain flow cytometer by forming a bend in a flow cell channel
Implementation Method 3
selecting an excitation filter and an emission filter configured to minimize Raman scattering from the liquid media
Implementation Method 4
illumination beam positioned to illuminate, through the transparent element, at least a portion of the sample and thereby particles in the sample
Implementation Method 5
an imager for imaging an area in a focal plane transverse to the flow axis within the portion of the sample illuminated by the illumination beam
Implementation Method 6
focusing illumination tightly onto the focal plane to limit illuminated volume and reduce scattered light
Data Source
AI summary
Methods and apparatus for improving signal-to-noise ratio in a Fountain Flow cytometer by reducing the background light intensity. One approach includes constraining an interrogated volume of the sample (e.g., by adding a light absorbing reagent to the sample or introducing a bend into a flow cell through which the sample flows). Another approach includes minimizing Raman scattering from the sample by choosing an excitation filter and an emission filter configured to narrowly encompass light at wavelengths within system excitation and emission peaks.