Dual-Mode Spectrophotometer Variable Optical Path
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Solution Overview
Problem
Current spectrophotometric methods are limited in handling small biological samples, often requiring large volumes and resulting in sample loss and measurement errors due to air-interface bubbles, with limited dynamic range for concentration measurement, especially for DNA/RNA samples.
Innovation Solution
A dual-mode spectrophotometer capable of measuring samples in both cuvette and surface-tension modes, allowing for optical path lengths from 10 micrometers to 25 millimeters, enabling absorbance measurement from 0.005 to 2.0 Absorbance Units, and facilitating cross-calibration with conventional instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cuvette-based methods are used to measure samples, then measurement precision can be maintained, but sample volume requirement increases to mL level causing sample loss
Solution Approach 1:
The patent changes the optical path length parameter from conventional 10mm or 2mm to a range of 0.2-2mm, enabling precise measurement of micro-liter scale samples without requiring mL-level volumes. This parameter change allows the system to maintain measurement precision while dramatically reducing sample consumption.
2Ease of operation
If samples are directed into cuvettes for measurement, then optical measurement can be performed, but air-interface bubble interfaces are produced causing measurement errors
Solution Approach 1:
The patent extracts and eliminates the air-liquid interface by using a sealed measurement chamber where the sample is contained between two optical windows. This removes the source of bubble formation and air-interface artifacts that plague conventional cuvette-based methods, thereby improving measurement precision.
3Productivity
If fixed path length cuvettes (2mm or 10mm) are used, then measurement can be performed, but dynamic range for absorbance measurement is limited to 1000 ng/ml for DNA/RNA samples
Solution Approach 1:
The patent introduces a variable optical path length mechanism that can dynamically adjust between 0.2mm and 2mm, enabling the system to adapt to different sample concentrations. For highly concentrated samples, a shorter path length prevents saturation, while for dilute samples, a longer path length enhances sensitivity, thereby expanding the measurable dynamic range beyond the fixed 1000 ng/ml limit.
4Loss of substance
If surface tension mode is used to reduce sample volume, then sample loss is reduced, but capability to handle larger sample volumes (up to 25mm path length) is lost
Solution Approach 1:
The patent creates a universal measurement system that can handle both micro-liter samples in surface tension mode and milliliter samples in cuvette mode within a single instrument. The system is designed to accept samples across the full range from 10 micrometers to 25 millimeters path length, eliminating the need for separate instruments and providing true multi-functionality.
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
Enables precise measurement of small and large sample volumes, reducing sample loss and measurement errors, and allowing for direct comparison with conventional methods, enhancing the dynamic range and accuracy of absorbance measurements.
Implementation Method 1
measuring absorbances from about 0.005 up to about 2.0 Absorbance Units for any given path length
Implementation Method 2
characterizing optical transmission and absorbance of large-volume as well as small-volume samples
Implementation Method 3
a smaller sample volume, which is incapable of being investigated in a cuvette-based apparatus, is held between two opposing substantially parallel surfaces by interfacial tension
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A dual-mode method and apparatus of selectively measuring samples (5, 5') in either a vessel (72) or as a surface tension retained sample (5) held between two opposing pedestals (A', A") is introduced. In either configuration, such modes further contain optical paths from a source system through a small-volume or large-volume sample to a spectrometer based system. Such a system enables a user to measure samples with absorbances ranging from about 0.005 up to about 2.0 Absorbance Units for any given wavelength.