Gas-Impermeable Cuvette for Sensitive Gaseous Analyte Detection
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Solution Overview
Problem
Existing methods for quantifying oxygen consumption or release in biological samples lack sensitivity and accuracy, especially for small samples, due to issues like high sample headspace capacity and rapid back-diffusion of ambient oxygen, making it difficult to measure low levels of gaseous analytes such as O2, CO2, or ammonia effectively.
Innovation Solution
A method and apparatus using a gas-impermeable cuvette with a narrow, elongate tube that is at least partly transparent, equipped with a probe sensitive to the gaseous analyte, where excitation radiation is directed at a sampling zone and emission radiation is measured to determine consumption or release, with temperature control and specific probe configurations to prevent diffusion and enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a closed test-vial with pressure sensor is used to quantify oxygen consumption, then oxygen consumption can be measured, but the method lacks sensitivity and accuracy for small samples due to high headspace capacity and rapid back-diffusion of ambient oxygen
Solution Approach 1:
The invention transitions from measuring pressure changes in a three-dimensional headspace volume to measuring optical properties (light absorption, fluorescence, or phosphorescence) in a two-dimensional planar geometry at the gas-liquid interface. This dimensional change eliminates the volume-related diffusion problem while maintaining measurement capability.
Solution Approach 2:
The invention replaces the mechanical pressure sensing system with an optical detection system. Instead of measuring pressure changes caused by oxygen consumption, the system uses optical probes to directly detect oxygen concentration changes at the interface, providing higher sensitivity and eliminating back-diffusion issues.
2Measurement precision
If a large headspace volume is used in the cuvette, then ambient oxygen diffusion into the sample is rapid, but if a small headspace is used, then the optical path length for measurement is insufficient
Solution Approach 1:
The invention measures optical properties in the planar interface dimension rather than along the vertical optical path dimension. By detecting light absorption, fluorescence, or phosphorescence at the gas-liquid interface, the system achieves high detection sensitivity without requiring a long optical path length through a large headspace volume.
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
This approach allows for sensitive and accurate monitoring of low levels of gaseous analyte consumption or release in small biological or chemical samples, preventing ambient oxygen influx and product diffusion, thereby detecting very small rates of analyte changes with high sensitivity and precision.
Implementation Method 1
a probe which is sensitive to the gaseous analyte... directing excitation radiation at a sampling zone of the tube and measuring emission radiation from the sampling zone
Implementation Method 2
The probe is based on a platinum(II)-porphyrin dye or a fluorescent ruthenium(II)-complex
Implementation Method 3
an elongate narrow tube which is substantially gas impermeable... preventing diffusion and enhance sensitivity
Implementation Method 4
providing a cuvette comprising an elongate narrow tube... the tube having a cross-sectional area of less than 2 mm2
Data Source
AI summary
A method for monitoring consumption or release of a gaseous analyte such as oxygen by a liquid sample under investigation includes providing a cuvette (1) having an elongate narrow tube (12) of a material which is substantially gas impermeable and which is at least partly transparent to measurement excitation radiation and emission radiation along some of the length of the tube. The tube (12) has a cross-sectional area of under 1 mm2. The sample (15) is loaded into the cuvette (1), the sample being in contact with a probe in the tube (12), the probe being sensitive to the gaseous analyte, and the liquid having at least one surface and an associated headspace (16). The cuvette, the sample, and the probe are equilibrated at a target measurement temperature. Excitation radiation is directed at a sampling zone of the tube (12) and which is distal from the headspace (16), while maintaining the cuvette at the measurement temperature. The emitted radiation is measured and analysed to determine consumption or release by the sample of the gaseous analyte.