Integrating Sphere Fluorescence Detection for qPCR Illumination
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Solution Overview
Problem
Current PCR devices face challenges with non-uniform illumination methods that are bulky, expensive, difficult to manufacture, fragile, or slow, leading to inaccurate fluorescence measurements due to spatial inhomogeneities and shadows.
Innovation Solution
The integration of a metallic integrating sphere with a white-color, light-diffusing interior and symmetric LED light sources provides uniform illumination of a 96-well PCR plate, using filter wheels to switch wavelengths and a CMOS camera for simultaneous fluorescence detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple-mirror reflection method is used for illumination, then fluorescence detection is achieved, but the device becomes bulky and expensive with difficult manufacturing
Solution Approach 1:
The patent introduces an integrating sphere as an intermediary optical component that receives light from a compact LED source and redistributes it uniformly across all sample wells. This mediator converts the simple point-source illumination into uniform multi-directional illumination, achieving the function previously requiring complex mirror systems while using a compact, manufacturable structure.
Solution Approach 2:
The patent changes the illumination parameters by using an integrating sphere to transform the spatial distribution and angular characteristics of light. The sphere converts unidirectional LED light into multi-directional uniform illumination, effectively changing the illumination parameters to achieve homogeneous lighting across all wells without requiring complex optical paths.
2Measurement precision
If distributed optical fibers are used for illumination, then fluorescence detection is achieved, but the system becomes fragile and difficult to manufacture
Solution Approach 1:
The integrating sphere serves as a robust intermediary that replaces the fragile optical fiber network. Instead of using hundreds of individual fibers that require precise alignment and are susceptible to damage, the sphere provides a single solid-state component that achieves the same uniform illumination function with much higher mechanical reliability and ease of manufacture.
Solution Approach 2:
The patent adopts a simpler, more replaceable illumination system based on LED and integrating sphere rather than expensive, fragile optical fibers. The LED-sphere combination is cheaper, more durable, and easier to replace if needed, aligning with the principle of using simpler, more reliable components over complex fragile systems.
3Measurement precision
If optical lens-beam-splitter-scanning method is used, then fluorescence signal acquisition is achieved, but the process becomes very slow
Solution Approach 1:
The patent uses excessive illumination by directing light into an integrating sphere that redistributes it to illuminate all sample wells simultaneously with uniform intensity. This excessive multi-directional illumination ensures that every well receives sufficient light at the same time, enabling parallel detection of all samples in a single camera exposure rather than sequential scanning.
Solution Approach 2:
The integrating sphere transforms the illumination from a one-dimensional scanning approach to a three-dimensional simultaneous illumination of all wells. By converting the light path through the sphere's interior, the system achieves uniform illumination across the entire plate at once, adding the dimension of parallelism and eliminating the time-consuming sequential scanning process.
4Measurement precision
If conventional illumination methods are used, then PCR sample illumination is achieved, but spatial inhomogeneities and shadows cause inaccurate fluorescence measurements
Solution Approach 1:
The integrating sphere acts as an optical mediator that receives light from the LED source and redistributes it uniformly in all directions. This intermediary component eliminates spatial inhomogeneities and shadows by scattering light multiple times within the sphere's diffuse reflective interior, ensuring homogeneous illumination across all sample wells for accurate fluorescence measurement.
Solution Approach 2:
The patent directly addresses illumination non-uniformity by using an integrating sphere that produces homogeneous light distribution. The sphere's diffuse reflective interior scatters light to create uniform intensity across the entire sample plate, eliminating the spatial inhomogeneities and shadows that plague conventional illumination methods and enable accurate fluorescence quantification.
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
Achieves cost-effective, compact, and efficient uniform illumination and fluorescence detection across multiple PCR samples, reducing manufacturing complexity and enhancing measurement accuracy.
Implementation Method 1
The inside of the integrating sphere 10 is coated with white-color light-diffusing material to scatter photons into all directions
Implementation Method 2
The light beam entering the sphere will be eventually uniformly distributed on the inner surface of the sphere after multiple scatterings
Implementation Method 3
Two excitation light sources 110 and 120, which are LED light sources, are mounted symmetrically on the integrating sphere 10
Implementation Method 4
fluorescence emission light is measured as indication of detected DNA quantity
Implementation Method 5
The corresponding fluorescence emission light is detected by a CMOS camera
Data Source
AI summary
The present invention is an integrating sphere-based fluorescence detection system for real-time quantitative PCR device comprising various components, including PCR sample reaction plate, illumination sources configured to produce excitation light, detection source configured to detect fluorescence emission light produced, in response to the excitation light from the sample reaction plate, an integrating sphere configured to direct the excitation light to the sample plate uniformly and to direct the fluorescence emission light from the sample holder along a response path to the imaging module. The system may enhance the quality of excitation light hitting samples in the sample holder.