Hinged Septum Flap Liquid Dispensing
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Solution Overview
Problem
Current methods for dispensing liquid fractions in chromatographical processes face challenges such as contamination, uneven distribution, and incompatibility with varying vessel sizes due to issues with surface tension, flow rates, and valve limitations, especially at microvolumetric flow rates.
Innovation Solution
A hinged septum with a flexible, elastic flap is used, allowing precise control over liquid deposition and sealing, eliminating contamination risks and accommodating various vessel sizes by automatically sealing and directing liquid droplets into collection chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hollow needles are used to deposit liquid droplets on vessel bases or liquid surfaces, then liquid distribution can be achieved, but contamination of the needle side wall occurs and carry over to the next fraction happens
Solution Approach 1:
A Teflon-coated needle is introduced as an intermediary material between the liquid sample and the needle surface. The Teflon coating acts as a non-stick barrier that prevents liquid from adhering to the needle side walls, thereby eliminating contamination and carry over while maintaining the needle's liquid delivery function.
2Productivity
If droplets are wiped off on side walls of collection vessels, then liquid distribution is achieved, but additional needle manipulation is required and the method is inapplicable to vessels with tapering walls
Solution Approach 1:
The needle is designed with a self-wiping capability where the liquid automatically flows down the needle surface due to gravity and surface tension, and the needle's movement through the vessel causes the liquid to be passively distributed along the walls without requiring additional manual manipulation or complex control mechanisms.
3Productivity
If 3/2-way valves are used for high volume flow rates, then liquid diversion to waste collection is achieved, but the valves cause increased external band broadening and excess volume at microvolumetric flow rates
Solution Approach 1:
The valve component is completely removed from the system. Instead of using a 3/2-way valve for liquid diversion, the invention employs a direct needle-based delivery system where liquid is deposited directly into collection vessels or diverted to waste containers without passing through a valve, thereby eliminating the source of band broadening and excess volume.
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 hinged septum enables well-defined initial and final conditions for liquid fractions, preventing contamination and ensuring accurate distribution across different vessel sizes, even at low flow rates, by using a hollow needle to open and close the flap, ensuring reliable sealing and efficient liquid collection.
Implementation Method 1
a hollow needle to be employed for depositing liquid to be collected may simultaneously be employed as a means for opening the septum's flap. The tip of the hollow needle may be positioned on the contacting and drainage surface on the foil on the flap and subsequently translated further forward, toward the second chamber, thereby opening the flap
Implementation Method 2
The elastic restoring force exerted by the springy, elastic hinge allows the flap to close automatically and seal the second chamber in order to prevent liquid that was previously injected into the second chamber from inadvertently leaking out
Implementation Method 3
A liquid buffer, having a volume ranging from 3 μl to 20 μl, may be formed on the tip of the hollow needle in order to counteract the surface tension of the liquid
Data Source
AI summary
For dispensing volumes of liquids, a hinged septum has a flap inclined with respect to the longitudinal axis of a liquid channel. A deposition device deposits liquid on the flap, wherein the deposition device is arranged to contact the flap.