Autosampler Needle Shaking-Off Mechanism
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Solution Overview
Problem
Existing autosamplers for liquid chromatographs face contamination issues due to liquid adhering to the outer surface of the needle after sampling, especially when the needle is inserted deep into liquid.
Innovation Solution
The autosampler incorporates a shaking-off step where the needle is repeatedly lowered and suddenly stopped while maintaining the suction port above the liquid level, effectively removing liquid from the outer surface of the needle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the needle is inserted deep into the liquid for sampling, then the sampling capability is improved, but liquid adheres to the outer surface of the needle causing contamination
Solution Approach 1:
The patent applies mechanical vibration by repeatedly lowering and suddenly stopping the needle (shaking-off operation) to generate inertial forces that detach liquid from the needle's outer surface. This vibration-based approach effectively removes adhering liquid without requiring additional wiping mechanisms, thus resolving the contradiction between deep insertion for sampling and preventing contamination.
Solution Approach 2:
The patent implements preliminary anti-action by performing the shaking-off operation after sampling to preemptively remove liquid before it can cause contamination. By anticipating the contamination problem and applying counter-action (shaking off liquid) immediately after sampling, the system prevents harmful effects before they occur.
2Device complexity
If a single shaking-off operation is performed, then the structure is simple, but liquid remaining on the needle outer surface causes contamination
Solution Approach 1:
The patent employs periodic action by repeating the shaking-off operation multiple times rather than performing it once. This periodic repetition ensures that liquid adhering at different positions and times is systematically removed, guaranteeing thorough contamination prevention while maintaining operational simplicity.
Solution Approach 2:
The patent applies partial or excessive action by performing more shaking-off operations than the minimum single operation. This excessive action (multiple repetitions) ensures complete liquid removal even though one operation might suffice for simple cases, thereby handling the variability in liquid adhesion conditions effectively.
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 approach ensures that liquid is effectively removed from the needle's outer surface, reducing contamination risks and maintaining device cleanliness.
Implementation Method 1
shaking-off operation of lowering and suddenly stopping the needle a plurality of times
Data Source
AI summary
A sampling needle (2) having a suction port at a tip, a movement mechanism (4) that moves the needle (2) at least in a vertical direction while holding the needle (2) in a state where the suction port faces vertically downward, a suction mechanism (6) for sucking liquid through the needle (2), a controller (10) configured to control operation of the movement mechanism (4) and the suction mechanism (6) are included. In sampling of liquid from a container (16) whose upper surface is opened, the controller (10) is configured to execute an inserting step of inserting the tip of the needle (2) into the liquid in the container (16) by lowering the needle (2) from above the container (16), a sucking step of sucking a predetermined amount of the liquid from the suction port of the needle (2) after the inserting step is completed, a pulling up step of pulling up the needle (2) from the liquid to position the suction port above a liquid level of the liquid after the sucking step is completed, and a shaking-off step of repeating shaking-off operation of lowering and suddenly stopping the needle (2) a plurality of times with standby time in which the needle (2) is completely stopped or raised in between while maintaining a state where the suction port is positioned above the liquid level after the pulling up step is completed.