Flow Cytometer Nozzle Assembly with Elliptical Cross-Section
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Solution Overview
Problem
Flow cytometer nozzle assemblies often fail to meet performance criteria due to irregularities in injection tube placement and presence of dead volumes, which affect fluid flow and sample orientation, leading to reduced nozzle performance and potential bacterial contamination.
Innovation Solution
The method involves over molding a straight injection tube into the nozzle assembly to ensure precise length and position, reducing dead spaces and using a nozzle design with an elliptical cross-section to promote uniform particle orientation and efficient fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional injection tube placement methods are used, then manufacturing flexibility is maintained, but manufacturing precision deteriorates due to irregularities in injection tube placement
Solution Approach 1:
The injection tube is integrated directly into the nozzle body as a single molded component, eliminating separate placement steps and ensuring consistent positioning. The mold cavity is designed to form both the nozzle housing and injection tube as one unified structure, resolving the contradiction between manufacturing precision and device complexity.
Solution Approach 2:
The injection tube position is predetermined during the molding process itself, with the mold cavity pre-configured to create the exact desired geometry and placement. This preliminary action during manufacturing ensures precise injection tube integration without requiring post-manufacturing adjustment or assembly steps.
2Reliability
If conventional nozzle design is used, then manufacturing simplicity is maintained, but reliability deteriorates due to dead volumes causing bacterial contamination
Solution Approach 1:
Dead volumes are completely eliminated from the nozzle design by creating a streamlined internal flow path that extends to the very tip of the nozzle. The injection tube is positioned and sized to leave no stagnant fluid regions, extracting the harmful dead volume elements from the conventional design while maintaining manufacturing simplicity through single-shot molding.
3Measurement precision
If standard circular nozzle cross-section is used, then manufacturing ease is maintained, but measurement precision deteriorates due to poor particle orientation
Solution Approach 1:
The nozzle cross-section is designed with an elliptical or asymmetric geometry rather than a standard circle, creating specific flow patterns that promote uniform particle orientation. This asymmetric design improves measurement precision for aspherical particles while the elliptical mold cavity remains straightforward to manufacture using conventional injection molding techniques.
Data Source
AI summary
A method of sorting cells including magnetically coupling a nozzle assembly to a flow cytometer in a predetermined orientation to form a fluid stream having a sheath fluid and a sample fluid. Particles within the sample fluid are oriented and then interrogated at an inspection zone to produces signals representative of emitted or reflected electromagnetic radiation. The electromagnetic radiation is analyzed to classify the cells and the cells are sorted according to their classification.