Flow Cell Meniscus Pressure Control for Trace Liquid Feed
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Solution Overview
Problem
The existing liquid feed control methods in flow cells are complex and prone to time delays and water hammer due to the small size of the flow cell and the delicate operation required for precise liquid handling, especially when residual pressures in pipes affect the pumping process.
Innovation Solution
A flow cell design featuring a concave portion and a channel where the meniscus of the liquid applies either a positive or negative pressure with an absolute value smaller than the pressure applied by the pump, allowing for easier control of liquid feed by creating a pressure differential that facilitates the movement of liquid between the introduction and delivery portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pump is used to transfer a trace amount of sample solution in a flow cell, then the liquid feed can be controlled, but the operation becomes complex and prone to time delays and water hammer due to the small size of the flow cell and residual pressures in pipes
Solution Approach 1:
The invention extracts the liquid transfer function from the pump and assigns it to the channel structure itself. The channel is designed with specific geometric features (narrow width, hydrophilic coating) that enable it to autonomously transfer liquid through capillary action, eliminating the need for complex pump operation in small flow cells
Solution Approach 2:
The channel structure serves itself by incorporating intrinsic liquid transfer capabilities through its geometric design and surface properties. The channel automatically draws liquid from the reservoir to the detection region using capillary forces generated by its narrow dimensions and hydrophilic coating, without requiring external pump control
2Measurement precision
If the flow cell is made very small to handle trace amounts of liquid, then measurement sensitivity is improved, but the pump operation becomes more delicate and complex due to residual pressures and small volumes
Solution Approach 1:
The invention replaces the mechanical pump system with a passive capillary-driven system. The channel's geometric structure and surface properties generate capillary forces that substitute for mechanical pumping, enabling trace liquid handling in small flow cells without the complexity of pump control
Solution Approach 2:
The invention changes the physical parameters of the channel (narrow width, hydrophilic surface properties) to generate sufficient capillary pressure for liquid transfer. This parameter modification enables the channel to overcome residual pressures and transfer liquid effectively in the small volume environment of miniaturized flow cells
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 enables more straightforward control of trace liquid feed, reducing the need for delicate pump operation and minimizing time delays, as the pressure applied by the meniscus in the channel stops the liquid movement when it exceeds the pump-generated pressure, allowing for efficient liquid handling without complex pump operation.
Implementation Method 1
the channel causes a meniscus of a liquid introduced into the channel to apply a negative pressure to the liquid
Implementation Method 2
the concave portion causes a meniscus of a liquid introduced into the concave portion to apply, to the liquid, one of a positive pressure and a negative pressure
Data Source
AI summary
A flow cell (2) includes a plate-shaped body 21 that is almost rectangular in a plan view, an introduction portion (22) that is made of a concave portion formed in the upper surface of the body (21), a channel (23) that is formed inside the body (21) and has one end connected to the lower end of the introduction portion (22), and a delivery portion (24) that is made of a concave portion formed in the body (21) and has the lower end connected to the other end of the channel (23). The introduction portion (22) is formed to cause the meniscus of a liquid introduced from an opening to apply, to the liquid, a positive pressure or a negative pressure whose absolute value is smaller than that of a negative pressure applied to the liquid introduced into the channel (23) by the meniscus of the liquid. The channel (23) is formed to cause the meniscus of the liquid introduced into the channel (23) to apply a negative pressure to the liquid. This invention provides a flow cell and a liquid feed system capable of more easily controlling feed of a trace amount of liquid.