Pipetting Needle Foam Piercing for Analyzer Accuracy
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Solution Overview
Problem
Foam formation on liquid surfaces in reagent containers leads to inaccurate fill level detection, causing pipetting inaccuracies and erroneous measurement results in automatic analysis devices, as existing methods often trigger alarms or require container replacement.
Innovation Solution
A method where the pipetting needle is repeatedly immersed and withdrawn without aspirating liquid if an implausible fill level is detected, allowing the needle to pierce through foam and ensuring precise liquid removal, which can be implemented using existing automatic analysis devices with level sensors and control software.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a level sensor is used to detect fill level, then the fill level can be determined, but foam formation causes incorrect detection and pipetting inaccuracies
Solution Approach 1:
The method performs preliminary actions by repeatedly measuring the fill level before actual pipetting. When foam is detected (indicated by implausible fill level values), the system preemptively agitates the liquid to eliminate foam before the problematic measurement is used for pipetting control, preventing pipetting inaccuracies before they occur.
Solution Approach 2:
The method converts the harmful effect of foam into a beneficial detection mechanism. By recognizing that foam causes implausible fill level readings (either too high or fluctuating), the system uses these erroneous measurements as indicators to trigger liquid agitation, thereby eliminating the foam and improving subsequent measurement accuracy.
2Manufacturing precision
If the pipetting needle is repeatedly immersed to pierce foam, then precise liquid removal is enabled, but time is lost due to multiple immersion cycles
Solution Approach 1:
The method performs preliminary liquid agitation when foam is detected before the actual liquid transfer. This preliminary action eliminates foam in advance, ensuring that subsequent fill level measurements and pipetting operations proceed without interruption or repeated immersion cycles, thereby reducing overall processing time.
Solution Approach 2:
The method implements feedback by continuously monitoring fill level measurements and comparing them against expected ranges. When implausible values indicate foam presence, the system triggers liquid agitation and re-measures, creating a closed-loop control that automatically resolves measurement errors and ensures accurate pipetting.
3Measurement precision
If alarms or container replacement is triggered by implausible fill levels, then measurement accuracy is protected, but device throughput decreases
Solution Approach 1:
The method performs preliminary liquid agitation when foam is detected, resolving the measurement issue before it can trigger alarms or container replacement. This preventive approach maintains measurement accuracy while avoiding interruptions to the analytical workflow, thereby preserving device throughput.
Solution Approach 2:
The method converts potentially harmful foam formation into a beneficial trigger for liquid agitation. By using implausible fill level measurements as indicators rather than causes for alarm, the system proactively eliminates foam through agitation, maintaining both measurement accuracy and continuous operation without interrupting workflow.
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 method enables precise liquid transfer even with implausible fill levels due to foam, avoiding unnecessary alarms and container replacements, thus maintaining device throughput and accuracy.
Implementation Method 1
The most common method for level determination is capacitive level determination. For this purpose, the pipetting needle consists of an electrically conductive material and thus basically forms the measuring electrode, and it also includes a reference electrode. The fill level can be continuously determined from the change in the electrical capacitance between the pipetting needle and the reference electrode.
Implementation Method 2
Another method is optical fill level determination. For this purpose, the pipetting needle includes an optoelectronic filling level sensor consisting of a light source and a light sensor. When immersed, the light is refracted by the liquid and no longer reaches the light sensor, or only weakly. The fill level can be determined from the weakening of the light signal.
Implementation Method 3
a height-adjustable pipetting needle which is arranged vertically on a movable or pivotable transfer arm and is connected to a pump unit, so that the pipetting needle can be used to remove a desired volume of liquid from a container and deliver it to a target container at another location
Data Source
Figure 1~2
AI summary
The present invention lies in the field of automated analytical instruments and relates to a method for transferring a volume of liquid from a first liquid vessel to a second liquid vessel. The method ensures increased pipetting accuracy even from liquid vessels (1) that have foam (3) on the surface of the liquid (2).