Single-Piece Injection Molded Sample Cell for Gas Flow Optimization
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Solution Overview
Problem
Existing capnograph devices face challenges with contamination buildup in non-disposable sample cells, leading to inaccurate CO2 measurements and increased manufacturing costs due to complex assembly and potential gas leakage.
Innovation Solution
A single-piece injection molded sample cell with parallel gas inlet and outlet lumens orthogonal to the optical axis, featuring curved walls and tapers to improve gas flow and reduce turbulence, along with a manufacturing method using mold pins to define the gas flow path, allowing for simplified assembly and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional multi-component sample cells are assembled, then functionality is achieved, but manufacturing complexity and assembly complexity increase
Solution Approach 1:
The patent combines multiple separate components (main body, inlet window, outlet window, inlet lumen, outlet lumen) into a single integrated sample cell structure. This merging eliminates the need for separate assembly steps, reduces the number of parts, and simplifies manufacturing while maintaining all necessary functional elements for gas sampling and optical measurement.
Solution Approach 2:
The single-piece sample cell structure performs multiple functions simultaneously: it provides the main body housing, contains the gas flow path with inlet and outlet lumens, and incorporates the optical measurement chamber with window openings. This multi-functional integration reduces assembly complexity while achieving complete functionality.
2Measurement precision
If non-disposable sample cells are used, then manufacturing cost is reduced, but contamination buildup leads to measurement inaccuracy
Solution Approach 1:
The patent employs a disposable sample cell design where the entire cell is discarded after a single use or limited number of uses. This eliminates contamination buildup issues by ensuring each cell is fresh and uncontaminated, maintaining measurement accuracy. The simplified single-piece structure makes the disposable cell cost-effective despite being non-reusable.
3Reliability
If complex assembly procedures are used, then component fit is improved, but manufacturing cost and time increase
Solution Approach 1:
By merging all components into a single molded piece, the patent eliminates interfaces between separate parts where gas leaks could occur. The integrated structure ensures gas-tight construction through the molding process itself, maintaining reliability while dramatically improving manufacturing efficiency by eliminating assembly steps.
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 provides more accurate and timely CO2 measurements with reduced latency and memory effects, while offering a disposable or non-disposable sample cell with improved handling and manufacturing efficiency, minimizing contamination and assembly complexity.
Implementation Method 1
The single-piece injection molded main body defines a gas flow path including an optical sampling bore with opposite inlet and outlet ends, wherein the optical sampling bore defines an optical axis, and the gas inlet lumen and the gas outlet lumen are parallel to each other and are both orthogonal to the optical axis
Data Source
Figure 1
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Figure 3(a)~3(g)
AI summary
A sample cell (10) for a respired gas sensor has a single-piece injection molded main body (40) defining a gas flow path including an optical sampling bore (42), a gas inlet lumen (50) connected with the inlet end (44) of the optical sampling bore, and a gas outlet lumen (52) connected with the outlet end (46) of the optical sampling bore. The gas flow path includes at least two curved walls (100, 102, 104, 106). The sample cell may be manufactured by assembling mold pins (120, 122, 124, 126, 128) for defining the gas flow path wherein at least two mold pins (122, 124) have curved surfaces for defining the at least two curved walls of the gas flow path, and injection molding the single piece injection molded main body including removing the mold pins after defining the gas flow path including the at least two curved walls.