UV LED Fiber Bundles for Compact Absorbance Measurement
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Solution Overview
Problem
Existing UV light sources for analytical instruments are large, unstable, generate heat, require high voltages, and lack sensitivity, linearity, and dynamic range due to insufficient use of band pass filters and reference detectors, making them unsuitable for miniaturization and accurate measurement of substances like proteins and nucleic acids.
Innovation Solution
A compact apparatus using AlGaN/GaN LEDs with optical fiber bundles and band pass filters to control light output, allowing selective wavelength transmission to flow cells, and a controller to manage LED operation, eliminating the need for additional components like beam splitters and providing a reference detector for intensity compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional UV light sources (mercury-lamp, deuterium lamp, xenon flash lamp) are used, then UV light for detection can be generated, but the instruments become large, unstable, and generate significant heat requiring high voltages
Solution Approach 1:
The patent changes the fundamental parameter of the light source from traditional UV lamps to LEDs emitting in the UV-A and UV-B ranges. This parameter change enables compact size, reduced heat generation, and elimination of high voltage requirements while maintaining UV light output capability for detection applications
Solution Approach 2:
The patent replaces the mechanical/electrical system of traditional UV lamps (requiring high voltage, generating heat, with limited lifetime) with a solid-state LED system. This substitution eliminates the need for complex voltage regulation, cooling systems, and extends operational lifetime significantly
2Illumination intensity
If traditional UV light sources are used without proper filtering, then light output is sufficient, but sensitivity, linearity, and dynamic range are insufficient for accurate measurement
Solution Approach 1:
The patent introduces band pass filters as intermediary components between the LED light sources and the sample. These filters selectively transmit specific wavelength ranges (e.g., 300-400 nm for UV-A, 200-300 nm for UV-B) while blocking other wavelengths, thereby improving measurement precision by ensuring that only the desired spectral components reach the sample and detector
Solution Approach 2:
The patent implements a reference detector that receives light through a reference flow cell without sample. This reference detector provides feedback signal that compensates for fluctuations in LED output intensity and spectral characteristics, thereby maintaining measurement linearity and dynamic range across varying operating conditions
3Device complexity
If LED light sources are used without band pass filters and reference detectors, then the apparatus is simpler, but the measurement lacks sensitivity, linearity, and dynamic range
Solution Approach 1:
The patent segments the optical path into distinct functional sections: LED light sources with individual band pass filters for wavelength selection, sample flow cells for measurement, and reference flow cells with reference detectors for compensation. This segmentation allows each component to perform its specific function efficiently while maintaining overall system simplicity
Solution Approach 2:
The patent designs the system where the reference detector automatically compensates for LED output variations without requiring external calibration or adjustment. The dual-flow cell configuration enables self-referencing measurements where the reference channel continuously monitors and corrects for source instability, maintaining measurement quality with minimal additional complexity
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 apparatus achieves efficient, cost-effective, and compact measurement of substance concentration with improved sensitivity, linearity, and dynamic range by using LEDs with optical fiber bundles and band pass filters, enabling accurate absorbance determination of substances like proteins and nucleic acids.
Implementation Method 1
light emitting diodes (LED) of type AlGaN/GaN with emissions in the 250 nm to 365 nm range have been developed
Implementation Method 2
an optical fiber bundle, the bundle comprising a plurality of optical fibers, arranged so that one optical fiber from each LED is connected to each flow cell
Implementation Method 3
Each LED is arranged with a corresponding band pass filter that transmits only a specific wavelength range
Implementation Method 4
Many substances absorb ultra violet or visible light due to their chemical composition. The absorption of light by substances has been used as the basis for detecting the presence of, and measuring the concentration of, such substances
Implementation Method 5
a UV detector (e.g. a photomultiplier or a photodiode) and changes in the intensity of UV light reaching the detector are related to the concentration of UV absorbing substances
Data Source
AI summary
An apparatus for measuring the absorbance of a substance in a solution includes at least one sample cell arranged to contain the solution that is at least partially transparent to light of a predefined wavelength spectrum, at least two light passages through the at least one sample cell, each of the light passages having a known path length, an LED light source arrangement including at least two LEDs, each arranged to emit a light output with a wavelength within the predefined wavelength spectrum. A plurality of optical fibers, one for each light passage, is arranged at each LED for receiving the light output and guiding it to the light passages. A method for measuring the absorbance of a substance in a solution includes providing the LED light source arrangement with an associate fiber bundle for each LED.