Pre-filmed Precision Sample Cell for X-ray Analysis
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Solution Overview
Problem
Existing sample handling cells for x-ray analysis of liquids face challenges in minimizing contamination, preventing operator-induced errors, and ensuring precise alignment of samples, particularly in applications requiring low detection limits and precise positioning.
Innovation Solution
A precision sample cell with a directional elastomeric fill valve and a spatially insulated film at the lower end, designed to prevent leakage and contamination, while allowing precise alignment and venting, ensuring accurate sample presentation to the x-ray analysis engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional sample cell is used for liquid samples, then the cell structure is simple, but contamination occurs on critical surfaces and operator errors increase
Solution Approach 1:
The sample cell is pre-assembled with the film already positioned and sealed to the reservoir bottom before arrival at the x-ray analyzer. The fill valve is pre-configured with directional flow characteristics. This preliminary preparation eliminates operator errors during assembly and ensures contamination-free critical surfaces by establishing proper seals and alignments before the sample is introduced.
Solution Approach 2:
A directional fill valve serves as an intermediary mechanism between the sample introduction system and the reservoir. This valve provides controlled unidirectional flow, preventing back-flow contamination while allowing sample entry. The valve acts as a mediator that manages the interface between external sampling operations and the contained sample, preventing operator-induced contamination.
2Reliability
If manual sample filling is used, then device complexity is low, but sample leakage and contamination occur
Solution Approach 1:
The directional fill valve is designed to automatically control sample flow based on pressure differentials and gravity. Once the sample is introduced through the valve, the directional characteristics prevent back-flow and leakage without requiring active control mechanisms. The valve self-regulates the filling process, preventing contamination and leakage while maintaining simple overall device architecture.
3Measurement precision
If precise z-axis alignment is not ensured, then device complexity is low, but measurement precision deteriorates due to focal spot sensitivity
Solution Approach 1:
The film is pre-positioned and sealed to the reservoir bottom at a precisely defined distance from the expected sample presentation plane. This preliminary positioning establishes the critical z-axis alignment reference before the sample is introduced. The pre-assembled configuration ensures that when the sample cell is placed in the analyzer, the sample automatically presents at the correct focal spot position without requiring complex alignment mechanisms.
4Measurement precision
If venting is not provided, then device complexity is low, but sample presentation precision is compromised due to pressure build-up
Solution Approach 1:
A venting pathway is integrated into the fill valve assembly, extracting the venting function from the main sample containment volume. The vent allows pressure equalization and air evacuation during filling without compromising the sealed containment of the sample. This separation of venting and containment functions maintains precise sample presentation while preventing pressure build-up that would otherwise distort the sample position.
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 minimizes contamination, reduces operator errors, and ensures precise alignment, thereby enhancing measurement accuracy and reliability in x-ray analysis systems, particularly in applications like sulfur detection in petroleum fuels.
Implementation Method 1
a directional fill valve disposed in an upper end of the outer body and forming an upper end of the sample reservoir, the fill valve for accepting a sample during filling, and preventing sample leakage while providing venting after filling
Implementation Method 2
The fill valve may be a one-way, elastomeric fill valve to accommodate a pipette during sample filling fixedly fastening the, preventing leakage of the sample upon removal of the pipette
Implementation Method 3
a film covering a lower end of the outer body, and forming a bottom end of the sample reservoir, the film for presenting the sample to an analysis focal spot of the analysis instrument
Data Source
AI summary
A sample cell for an analysis instrument, having an outer body forming a sample reservoir therein; a directional fill valve disposed in an upper end of the outer body and forming an upper end of the sample reservoir, the fill valve for accepting a sample during filling, and preventing sample leakage while providing venting after filling; and a film covering a lower end of the outer body, and forming a bottom end of the sample reservoir, the film for presenting the sample to an analysis focal spot of the analysis instrument. The disclosed sample cell is especially suited for an x-ray analysis engine having a focal spot requiring alignment with the sample in the sample cell. At least one x-ray optic may be disposed in an excitation and/or detection path, requiring alignment to the focal spot, in e.g., a WDXRF or EDXRF system.