Humidity Control via Selective Membrane in Sealed Sensing Cell
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Solution Overview
Problem
Permeation testing instruments face challenges in controlling humidity within the sensing cell, especially when using the accumulation method, as the sensing cell is sealed to fluid flow, which can affect the accuracy of permeation measurements through films sensitive to humidity.
Innovation Solution
A humidity control system is introduced, featuring a selectively permeable membrane that allows water vapor control while maintaining the target analyte's impermeability, allowing for precise humidity management within the sealed sensing cell by using a humidity control chamber in fluid communication with the sensing cell through the membrane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the sensing cell is sealed to fluid flow during accumulation method testing, then test time is reduced and sensor cost is lowered, but humidity control becomes impossible
Solution Approach 1:
The sensing cell is divided into two separate chambers: a sealed sensing chamber for analyte detection and a humidity control chamber for moisture regulation. The selectively permeable membrane acts as a partition that allows independent control of humidity without compromising the seal integrity, enabling both fast testing and humidity management.
Solution Approach 2:
A selectively permeable membrane serves as an intermediary between the humidity control chamber and the sealed sensing cell. This membrane allows water vapor to pass through for humidity control while blocking the target analyte, enabling indirect humidity regulation without breaking the seal or contaminating the sensing environment.
2Ease of operation
If a selectively permeable membrane is introduced for humidity control, then humidity can be controlled in sealed cells, but device complexity increases
Solution Approach 1:
The selectively permeable membrane performs multiple functions simultaneously: it separates the humidity control chamber from the sensing cell, allows water vapor transmission for humidity control, and blocks the target analyte from leaking. This multi-functionality reduces the need for additional separate components, mitigating the complexity increase.
Solution Approach 2:
The selectively permeable membrane is implemented as a thin film that can be integrated into the chamber structure. This approach minimizes the additional volume and structural complexity while achieving the desired selective permeability function, making the system more compact and manageable.
3Measurement precision
If electrochemical sensors are used for analyte detection, then accuracy and sensitivity are improved, but humidity sensitivity increases requiring complex control systems
Solution Approach 1:
The humidity control function is extracted from the sensing cell and placed in a separate humidity control chamber. This separation allows the electrochemical sensor to operate in a stable, controlled humidity environment without direct exposure to humidity variations, maintaining high accuracy while reducing humidity sensitivity issues.
Solution Approach 2:
The invention creates a controlled microenvironment within the sensing cell that replicates ideal testing conditions regardless of external humidity changes. The selectively permeable membrane acts as a barrier that copies/maintains the desired humidity level inside the sensing cell while allowing external humidity control through the separate chamber.
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 system enables consistent and accurate humidity control within the sensing cell, even when sealed to fluid flow, ensuring reliable permeation testing results by maintaining a controlled environment for the analyte permeation testing instrument.
Implementation Method 1
a selectively permeable membrane permeable to water vapor and impermeable to the target analyte
Implementation Method 2
a selectively permeable membrane permeable to water vapor and impermeable to the target analyte
Data Source
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AI summary
A humidity control system for an analyte permeation testing instrument. The system includes (i) an analyte permeation testing instrument, (ii) a sensor for sensing a target analyte, (iii) a humidity control chamber, and (iv) a selectively permeable membrane permeable to water vapor and impermeable to the target analyte. The analyte permeation testing instrument defines a testing chamber operable for engaging a test film such that the testing chamber is sealingly separated by the test film into a first cell and a second cell throughout a permeation testing period. The sensor is placed in fluid communication with the first cell. The humidity control chamber is positioned adjacent the first cell and in fluid communication with both a source of gas having a known humidity and the first cell, with the selectively permeable membrane sealingly separating the humidity control chamber from the first cell.