Variable Path Length Spectrometer for Undiluted Sample Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ultraviolet/visible spectrophotometers face challenges in accurately determining the concentration of highly concentrated biological samples without dilution, requiring extensive installation and space for variable path length spectroscopy systems.
Innovation Solution
A variable path length spectrophotometer system with a light source, optical probe, motor, and detector that dynamically adjusts measurement parameters based on the slope parameter derived from the rate of change in intensity with path length variation, allowing concentration determination without prior knowledge of path length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard cuvette with fixed path length is used, then the instrument structure is simple, but accurate concentration measurement of highly concentrated samples is difficult without dilution
Solution Approach 1:
The patent employs a variable path length cuvette with a movable plunger that can dynamically adjust the light path length through the sample. This dynamic adjustment capability allows the system to adapt to different sample concentrations, enabling accurate measurement of highly concentrated samples without dilution while maintaining a relatively simple overall instrument structure.
2Measurement precision
If multiple dilutions are performed to measure highly concentrated samples, then concentration can be measured within linear range, but dilution errors occur and sample is consumed
Solution Approach 1:
Instead of changing the sample concentration through dilution, the patent changes the measurement parameter by adjusting the path length of light through the sample. The variable path length cuvette allows the system to maintain the sample in its original concentrated state while adjusting the optical path length to bring the absorbance reading within the linear measurement range, thereby eliminating sample consumption and dilution errors.
3Measurement precision
If variable path length spectroscopy system is implemented, then accurate measurement of concentrated samples is enabled, but extensive installation space and complex instrumentation are required
Solution Approach 1:
The patent segments the variable path length adjustment function into a standalone accessory (the variable path length cuvette with movable plunger) that can be used with standard spectrophotometers. This segmentation allows the space-saving benefit to be achieved without requiring complete redesign of the entire spectrophotometer system, thus reducing installation space requirements while maintaining measurement accuracy.
4Measurement precision
If path length is known with great accuracy, then concentration measurement is accurate, but highly concentrated samples fall outside linear range
Solution Approach 1:
The patent transforms the fixed path length into a dynamic, adjustable parameter. The movable plunger in the variable path length cuvette enables continuous adjustment of the light path length, allowing the system to adapt to different sample concentrations. This dynamic capability expands the measurement range to accommodate highly concentrated samples while maintaining accurate concentration determination through the relationship between absorbance, path length, and concentration.
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 accurate concentration measurement of fluid samples in real-time, adjusting measurement parameters automatically to improve measurement quality and reduce installation space requirements.
Implementation Method 1
Absorption spectroscopy is used to measure composition and/or properties of a material in any phase, gas, liquid, solid. For example, the optical absorption spectra of liquid substances may be measured to determine concentration or other properties of a species of interest, within a liquid medium.
Implementation Method 2
For a sample consisting of a single homogeneous substance having a concentration c, the light transmitted through the sample will follow a relationship know as Beer's Law: A=εCL where A is the absorbance (also known as the optical density (OD) of the sample at wavelength λ where OD=the −log of the ratio of transmitted light to the incident light), & is the absorptivity or extinction coefficient (normally at constant at a given wavelength), C is the concentration of the sample, and L is the path length of light through the sample.
Implementation Method 3
a variable path length spectrophotometer has recently been developed. This type of spectroscopy system may generally employ a known light source, such as a source based upon a UV/visible spectrophotometer. Light from the UV/visible spectrophotometer is then directed to a special probe in an analysis instrument that is arranged to dynamically change the path length L in a special sample chamber during an absorbance measurement.
Data Source
AI summary
A system may include a light source, to generate a probe signal, comprising incident radiation; an optical probe, to direct the incident radiation through a fluid sample; a motor, to move the optical probe along a probe axis, to change a path length of the incident radiation through the fluid sample; and a detector, to receive the incident radiation as attenuated radiation after passing through the fluid sample. The system may include a control system, arranged to: initiate an absorbance measurement by directing movement of the optical probe along the probe axis; direct the light source to emit the incident radiation; and automatically adjust at least one measurement parameter of a set of measurement parameters for the sample measurement, based upon a slope parameter m, wherein m is derived from a rate of change in an intensity of the attenuated radiation with a change in the path length.