Optical Flow Cell Floating Seal for Path-Length Consistency
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Solution Overview
Problem
Existing optical flow cells for spectroscopic analysis of body fluids face issues with sample contamination and inconsistent optical path-length due to slidable or compressive mechanisms, affecting precision and repeatability.
Innovation Solution
A variable path length optical flow cell that expands and closes like a bellows, utilizing a diamond-shaped floating seal to maintain precise sealing without compression, ensuring accurate and repeatable optical path-length measurements by avoiding vertical compression of the seal between cell portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a slidable mechanism is used to adjust the flow path, then the sample can be flushed efficiently, but sample contamination occurs and dimensional consistency of path-length is affected
Solution Approach 1:
The flow cell is divided into two separate portions that can move independently relative to each other. The first portion contains the sample chamber and the second portion contains the flush channel, allowing each to be optimized for its specific function without interfering with the other.
Solution Approach 2:
A floating seal acts as an intermediary element between the first and second portions. This seal maintains fluid-tight coupling while allowing relative movement, preventing sample contamination during flushing operations.
2Productivity
If a compressive force is applied between cell portions to clear the sample, then the sample can be flushed, but the optical path-length is affected due to compression of the elastomeric gasket
Solution Approach 1:
The patent replaces the elastomeric gasket compression mechanism with a floating seal system that uses lateral expansion rather than vertical compression. The seal expands laterally against the walls of the flush channel, avoiding compression of any elastomeric material that would affect optical path-length.
Solution Approach 2:
Instead of applying compressive force in the vertical direction (which compresses the gasket and affects optical path-length), the floating seal uses lateral expansion in the horizontal direction to maintain sealing. This dimensional change allows flushing without compromising optical measurements.
3Ease of operation
If the flow cell is opened for flushing, then sample can be cleared efficiently, but the optical path-length becomes inconsistent
Solution Approach 1:
The flow cell design allows dynamic adjustment between a closed measurement state and an open flushing state. The floating seal enables the cell to transition smoothly between these states, maintaining sealing during flushing while preserving precise optical path-length during measurement.
Solution Approach 2:
The floating seal serves as a mediator that allows the flow cell to be opened for flushing without permanently compromising the optical path-length. The seal maintains fluid-tight coupling during both operational modes, ensuring measurement precision is preserved.
Data Source
AI summary
A sample cell apparatus for use in spectroscopic determination of an analyte in a body fluid sample includes a first plate member and a second plate member made from an optically clear material. A channel extending into a surface of the first plate member and an opposing surface of the second plate member houses a floating seal, which surrounds a fluid sample chamber. The fluid chamber is closed to define a repeatable optical path-length therethrough by urging the first plate member against the second plate member without compressing the floating seal between the first plate member and the second plate member. The seal channel is vented to prevent fluid pressure from flexing the first plate member or the second plate member. An actuator having an extended foot portion extends over the fluid chamber to help prevent flexing of the first plate member or the second plate member.