Pipetting Pressure Correction for Reliable Disposable Tip Metering
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Solution Overview
Problem
Existing pipetting devices face inaccuracies in quality assessment due to manufacturing tolerances and variable interactions between pipetting tips and working gas, leading to false-negative or false-positive assessments, especially with disposable tips changing metering characteristics.
Innovation Solution
A method involving a correction pressure determining process where the pipetting piston moves in the same direction as the metering process, capturing the working gas pressure to correct the temporal course, using a data correlation to adjust for variations in pipetting tip characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure target values range is chosen large to avoid false-negative quality assessments, then the reliability of quality assessment is improved, but the measurement precision deteriorates because deviations from the norm have to be especially significant to leave the enlarged pressure target values range
Solution Approach 1:
The patent applies preliminary action by determining a correction pressure before the actual metering process using the same pipetting tip. This correction pressure is then used to adjust the measured pressure values during metering, allowing for a more precise and reliable quality assessment without needing to enlarge the pressure target values range excessively.
Solution Approach 2:
The patent changes the parameter of pressure values by introducing a correction pressure that is subtracted from the measured pressure values during metering. This parameter transformation allows the system to maintain a reasonable pressure target values range while achieving both high reliability and measurement precision in quality assessment.
2Ease of operation
If disposable pipetting tips are used to maintain process hygiene, then the ease of operation and hygiene are improved, but the manufacturing precision deteriorates because each tip has different metering characteristics due to manufacturing tolerances and tip-duct interactions
Solution Approach 1:
The system performs a preliminary correction pressure determination with each disposable pipetting tip before actual metering. This preliminary action characterizes the specific interaction between the tip and duct, allowing the system to compensate for manufacturing tolerances and maintain consistent quality assessment across all disposable tips.
Solution Approach 2:
The correction pressure determination is integrated into the continuous workflow with each disposable tip, ensuring that the characterization and compensation happen automatically for every tip without interrupting the overall process hygiene benefits of using disposable components.
3Productivity
If the correction pressure determining process is performed at high piston velocity to maintain productivity, then the productivity is improved, but the measurement precision deteriorates because the pressure course differs from the actual metering process
Solution Approach 1:
The patent transforms the correction pressure determined at high velocity into an expected correction pressure at the actual metering velocity using a data correlation. This parameter transformation allows the system to use fast correction measurements while maintaining accuracy for the actual slower metering process.
Solution Approach 2:
The data correlation acts as an intermediary that bridges the gap between the fast correction pressure measurement and the actual metering process. It translates the high-velocity correction data into the equivalent correction for the actual metering velocity, maintaining both productivity and precision.
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
Enhances the accuracy of metering process quality assessment by accounting for individual pipetting tip interactions, reducing false assessments and maintaining productivity.
Implementation Method 1
A pressure sensor in order to capture the pressure of the working gas in the pipetting duct
Implementation Method 2
A pipetting piston accommodated movably in the pipetting duct in order to modify a pressure of the working gas in the pipetting duct through a piston movement
Data Source
AI summary
A method for the quality-assessed metering by means of a pipetting device, the method including the following steps:—carrying out a metering process by moving a pipetting plunger, —recording the time curve of the working-gas pressure in a pipetting channel during the metering process, —comparing the curve of the working-gas pressure on the basis of the recorded time curve of the working-gas pressure with a predetermined target pressure value range, and—outputting a quality assessment of the metering process on the basis of the result of the comparison step; in order to improve the quality assessment, the control device carries out the following further steps while the pipetting channel is filled exclusively with working gas as fluid:—carrying out corrective-pressure determination by moving the pipetting plunger, and—measuring a pressure of the working gas in the pipetting channel as a corrective pressure during the corrective-pressure determination, wherein, prior to the comparison step, the control device corrects the time curve of the working-gas pressure recorded during the metering process on the basis of the corrective pressure measured during the, so that the comparison step is carried out using the corrected time curve of the working-gas pressure.