Flow Cell Design for Optical Particle Analysis
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Solution Overview
Problem
Existing flow cell configurations for fluid analysis face challenges such as sample fluid mixing with sheath fluid, optical distortion, high production costs, and complex structures, which result in poor image quality and inefficient fluid management.
Innovation Solution
A flow cell design featuring a flow channel with a sample flow channel and at least one sheath flow channel, where the sheath fluid is introduced to press the sample fluid against a wall, creating a laminar flow and minimizing mixing, with a tapered section to spread the sample fluid thinly and a flattened section for clear imaging, and a measurement device incorporating this flow cell for precise fluid control and imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the sample fluid and sheath fluid are merged and constricted by a narrow flow channel, then the sample fluid can be flattened for imaging, but part of the sample fluid lies outside the focal range leading to poor image quality
Solution Approach 1:
The flow channel is divided into distinct functional sections: a merging section for fluid combination, a tapered section for gradual depth reduction, and a flattened section for imaging. This segmentation allows each section to optimize its function, ensuring the sample fluid remains within the focal range while achieving the necessary flattening for clear images.
Solution Approach 2:
The flow channel depth is varied locally along its length, with the merged section having greater depth and the flattened section having reduced depth. This local variation in geometry allows the sample fluid to be gradually compressed into the focal range without causing turbulence or loss of focus, thereby improving image quality while maintaining precision.
2Measurement precision
If a pump system is used to control fluids at high precision, then fluid control accuracy improves, but the device becomes complicated and costly
Solution Approach 1:
The flow cell design enables self-regulating fluid control through its geometric features. The tapered section naturally guides the sample fluid into the flattened section without requiring external pumping mechanisms. The sheath fluid automatically surrounds and constrains the sample fluid based on the channel geometry, achieving precise fluid control through passive design rather than active pump systems.
Solution Approach 2:
The pump system is completely removed from the flow cell design. Instead of using mechanical pumps to control fluid flow and positioning, the invention extracts this function and replaces it with carefully designed channel geometries that achieve the same control objectives through fluid dynamics alone, thereby reducing device complexity and cost.
3Reliability
If a large volume of sheath fluid is used to surround the sample, then the sample is well-supported for imaging, but optical distortion due to flow in the sheath fluid is captured, deteriorating image quality
Solution Approach 1:
The sheath fluid is positioned locally adjacent to the sample fluid only where needed for support and constraint. The flattened section geometry ensures the sheath fluid surrounds the sample fluid in a controlled manner without creating large volumes of flowing sheath fluid in the imaging path, thereby maintaining sample stability while minimizing optical distortion.
Solution Approach 2:
The problematic flowing sheath fluid is removed from the imaging region. The design extracts the sheath fluid from the focal plane area while maintaining its presence in the flattened section where it provides necessary support. This separation eliminates the source of optical distortion while preserving the stabilizing function.
4Reliability
If the flow cell has a large volume to accommodate sheath fluid, then the sheath fluid can effectively surround the sample, but sheath fluid consumption increases and production costs rise
Solution Approach 1:
The flow cell volume is reduced by changing the geometric parameters of the channel, particularly in the flattened section where the depth is minimized. This parameter optimization allows the sheath fluid to maintain its surrounding function while occupying a much smaller volume, thereby reducing fluid consumption and associated costs without compromising reliability.
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
This design allows for clear imaging of samples while suppressing mixing with sheath fluid, reducing optical distortion, and minimizing fluid consumption, leading to improved precision and cost-effectiveness in fluid analysis.
Implementation Method 1
creating a laminar flow and minimizing mixing
Implementation Method 2
The tapered section connects the flow merging section with the flattened section and gradually decreases in depth on progression downstream
Data Source
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AI summary
A flow cell including a flow channel through which a sample fluid and a sheath fluid flow, a sample flow channel that introduces the sample fluid into the flow channel, and at least one sheath flow channel that introduces the sheath fluid into the flow channel. The flow channel includes a flow merging section where the sample flow channel and the sheath flow channel merge, a flattened section that is disposed downstream of the flow merging section, that is formed in line with one wall face of wall faces facing across the flow merging section, and that is shallower in depth than the flow merging section, and a tapered section that connects the flow merging section with the flattened section and that gradually decreases in depth on progression downstream. The sample flow channel introduces the sample fluid into the flow merging section along the one wall face of the wall faces facing across the flow merging section, and the sheath flow channel introduces the sheath fluid into the flow merging section from a direction such that the sheath fluid flows so as to press the sample fluid against the one wall face.