Infrared Flow Cell Coating for Stable Aqueous Analyte Measurement
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Solution Overview
Problem
Conventional infrared (IR) systems struggle with measuring aqueous samples due to water's strong absorption of IR light, requiring complex fluidics and high pressures, and are prone to instability and calibration issues, making reproducibility and quantification difficult.
Innovation Solution
A device with chamber walls coated with copolymers containing functional groups like sulfonic acids and fluorinated hydrocarbon groups, which are inert and prevent molecule accumulation, allowing for constant measurement conditions and easy sample handling, using a thin, homogeneous coating to minimize optical path interference and maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional infrared systems are used to measure aqueous samples, then measurement can be performed, but water's strong absorption of IR light causes instability and requires complex fluidics and high pressures
Solution Approach 1:
The patent extracts the problematic interaction between water and IR light by using a flow cell design where the sample flows through a defined path between optical windows. This separates the measurement function from the complex fluid handling requirements, allowing simple flow-through measurement without needing complex fluidics or high pressures to maintain stable measurements despite water's strong IR absorption
Solution Approach 2:
The patent introduces an intermediary approach by using a flow cell with defined optical path length as a mediator between the IR source and detector. This flow cell design acts as a controlled environment that isolates the measurement from the complexities of water's absorption characteristics, enabling stable measurements without direct confrontation of water's strong IR absorption with complex system requirements
2Use of energy by moving object
If chamber walls are made of materials like CaF2 for IR transmission, then IR light can pass through, but the materials are easily attacked by acids and chelators in aqueous samples
Solution Approach 1:
The patent applies the disposable principle by using flow cell chambers that can be easily replaced rather than requiring permanently stable, chemically resistant materials. The flow cell design allows the chamber to be discarded after use, eliminating the need for expensive, chemically resistant materials like specialized coated CaF2 windows, while maintaining IR transmission capability through standard optical window materials
Solution Approach 2:
The patent changes the material parameter by transitioning from chemically resistant but IR-transparent materials like coated CaF2 to standard optical window materials that are less resistant but can be easily replaced. This parameter change in material selection allows the system to maintain IR transmission while accepting lower chemical resistance, compensated by the disposable nature of the flow cell chamber
3Measurement precision
If background measurements are performed regularly for calibration, then measurement accuracy can be maintained, but this requires complex fluidics or rinsing of the cell and high pressures
Solution Approach 1:
The patent applies self-service by designing the flow cell to automatically handle calibration through simple flow-through operation. The system performs background and sample measurements sequentially as the sample flows through the cell, eliminating the need for complex fluidics or manual rinsing operations. The flow cell itself serves the calibration function without requiring additional complex fluid handling systems
Solution Approach 2:
The patent extracts the calibration function from complex fluidics by implementing it through simple sequential measurement of background and sample as the sample flows through the flow cell. This separation allows calibration to be performed without requiring complex fluid handling, rinsing operations, or high pressures, maintaining measurement precision through a simplified approach
4Measurement precision
If layer thickness of the sample must be controlled to within 1 nm for comparable measurements, then measurement reproducibility is achieved, but this requires very high pressures and complex control systems
Solution Approach 1:
The patent applies preliminary action by pre-defining the optical path length through the flow cell design before measurements are taken. The flow cell is manufactured with a precise, fixed path length that establishes the measurement geometry in advance, eliminating the need for complex real-time control systems to maintain thickness within 1 nm. The preliminary manufacturing precision of the flow cell itself provides the required reproducibility
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 solution enables stable, long-term valid calibration data, reducing costs and complexity, allowing for disposable or low-cost systems with high reproducibility and comparability of measurements, achieving over 99% identical readings in consecutive measurements.
Implementation Method 1
the surfaces of the IR measurement chamber adjacent to the sample have the property of binding molecules contained in the sample
Implementation Method 2
Measurements in the infrared (IR) range allow a large number of determinations on complex analytes
Implementation Method 3
the at least one chamber wall having a homogeneous coating permeable to infrared radiation on its surface adjacent to the inner cavity
Data Source
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AI summary
An apparatus (1) for determining the concentration of at least one analyte contained in a sample using infrared absorption measurement and/or transmission measurement has a measurement chamber having an inner cavity (4) for holding the sample. The inner cavity (4) is delimited by at least one chamber wall (2, 3), which is transparent to infrared radiation. The at least one chamber wall (2, 3) has, on its surface which adjoins the inner cavity (4), an inert coating (11, 12) which is transparent to infrared radiation. The coating is extremely thin and homogeneous. It prevents as far as possible deposits of foreign substances on the surface and has a particular configuration with which the sample filling and the sample interchange and the cleaning are particularly simple.