Spectrophotometric Instrument With Flexible TPE Cell Cradle
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Solution Overview
Problem
Movement of the sample cell during measurement or adjustment of its position causes unwanted deviations in spectrophotometric measurements due to manufacturing tolerances, particularly in the diameter of the cylindrical sample cell, which is the largest dimensional variable affecting accuracy.
Innovation Solution
A spectrophotometric instrument with a flexible restraining cradle made of thermoplastic elastomer (TPE) that accommodates the sample cell, ensuring alignment and providing a seal, while accommodating varying dimensions and minimizing friction, using features like an annular collar, pillars, and end stops to centralize and stabilize the cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rigid restraining structure is used to hold the sample cell, then alignment precision is improved, but the device cannot accommodate varying sample cell dimensions and manufacturing tolerances
Solution Approach 1:
The patent employs a flexible restraining cradle made of thermoplastic elastomer (TPE) material that can adapt to varying sample cell dimensions while maintaining alignment. The flexible nature of the cradle allows it to accommodate manufacturing tolerances (e.g., diameter variations of ±0.2 mm) without requiring rigid adjustment mechanisms, thus resolving the contradiction between alignment precision and adaptability.
Solution Approach 2:
The patent changes the physical state of the restraining material from rigid to flexible by selecting appropriate TPE compounds with specific durometer ranges (e.g., 70-90 Shore A). This parameter change enables the restraining cradle to deform elastically to fit different sample cell sizes while maintaining sufficient contact for alignment, thereby accommodating dimensional variations without sacrificing measurement precision.
2Adaptability or versatility
If a flexible restraining cradle is used to accommodate varying sample cell dimensions, then adaptability is improved, but friction increases during loading and unloading
Solution Approach 1:
The flexible TPE cradle is designed with specific material properties (durometer 70-90 Shore A) that provide enough flexibility to accommodate dimension variations but limited flexibility to minimize friction. The material selection balances adaptability with low friction characteristics, allowing smooth loading and unloading of sample cells while maintaining dimensional accommodation capability.
Solution Approach 2:
The restraining cradle is designed to be dynamically adjustable through elastic deformation. When a sample cell is inserted, the cradle deforms elastically to accommodate the cell's dimensions, then returns to its original shape to provide gentle restraining force. This dynamic behavior allows the system to adapt to varying dimensions while minimizing static friction during operation.
3Ease of operation
If the optical pot is made optically transparent for visibility, then ease of operation is improved, but the structural integrity and sealing capability are reduced
Solution Approach 1:
The optical pot is constructed from transparent polymethylmethacrylate (PMMA) material that combines optical transparency with sufficient structural strength. This composite material selection allows the pot to be both visible for ease of operation and structurally sound enough to maintain sealing integrity when combined with the flexible TPE cradle and instrument housing.
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 flexible restraining cradle ensures repeatable and accurate measurements by maintaining alignment and reducing friction, thus improving the performance and consistency of spectrophotometric instruments.
Implementation Method 1
a flexible restraining cradle mounted circumferentially on the optical pot in sealing engagement with the instrument housing, wherein the flexible restraining cradle is adapted to restrainedly accommodate the sample cell in the optical path
Implementation Method 2
The plurality of spaced apart pillars may act usefully as an optical barrier to limit stray electromagnetic radiation and internal reflections
Data Source
AI summary
A spectrophotometric instrument (1) for the quantitative measurement of an optical property of an analyte in a sample cell (4). The spectrophotometric instrument (1) comprises an instrument housing (2a, 2b) for a source of electromagnetic radiation and a detector; an optical pot (3) for accommodating the sample cell (4) having a flexible restraining cradle (6).