Peristaltic Pump Aspiration Calibration for Aging Tube Volume Accuracy
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Solution Overview
Problem
Existing liquid extraction systems in automated analyzers face challenges due to changing sensitivity in process control caused by peristaltic tube aging, leading to inaccurate volume measurement and unscheduled maintenance, despite efforts to maintain constant parameters.
Innovation Solution
A calibration method involving a known liquid volume aspiration using a peristaltic pump and bubble sensor to determine a calibration value, adjusting parameters for individual pump/hose combinations, and compensating for aging effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parameterized limits are set more generously to accommodate tolerances, then error robustness is improved, but measurement precision deteriorates
Solution Approach 1:
The system performs a preliminary calibration by measuring the actual aspiration time of a known liquid volume before conducting the main measurement. This preliminary action establishes a baseline that accounts for individual pump and hose variations, allowing subsequent measurements to be corrected relative to this baseline rather than relying on theoretical limits.
Solution Approach 2:
The system changes the reference parameter from fixed theoretical limits to dynamically determined calibration values. By measuring the actual aspiration time and using it as a reference, the system adapts the measurement parameters to the specific hardware configuration, resolving the contradiction between robustness and precision.
2Measurement precision
If pump parameters are kept constant to reduce variability, then measurement consistency is improved, but adaptability to aging components deteriorates
Solution Approach 1:
The system implements feedback by continuously monitoring the actual aspiration time and comparing it to the calibrated reference value. When deviations occur due to aging components, the system can detect these changes and trigger recalibration or maintenance alerts, maintaining measurement consistency while adapting to component degradation over time.
Solution Approach 2:
The system transitions from static fixed parameters to dynamic adaptive parameters. The calibration values are not fixed but can be updated based on actual measurements, allowing the system to adapt to aging components while maintaining measurement consistency through continuous reference updates.
3Ease of operation
If peristaltic tubes are used for liquid aspiration, then ease of operation is improved, but reliability deteriorates due to aging
Solution Approach 1:
The system performs a preliminary calibration measurement using the peristaltic tube and pump combination before actual liquid handling. This establishes a baseline that captures the specific characteristics of that tube, allowing the system to compensate for its aging behavior in subsequent operations, thereby maintaining reliability while preserving ease of operation.
Solution Approach 2:
The system enables the peristaltic tube to essentially self-calibrate by using its own performance characteristics during the calibration phase. The tube's actual aspiration behavior becomes the reference, allowing the system to automatically compensate for the tube's aging without requiring manual intervention or tube replacement, thus maintaining reliability while preserving operational simplicity.
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 accuracy and sensitivity of liquid volume measurement, reduces unscheduled maintenance, and extends the service life of peristaltic tubes by adapting parameters to changing conditions.
Implementation Method 1
The sensor is configured to optically detect transitions from air to liquid in the extraction hose comprising the liquid
Implementation Method 2
a peristaltic pump, and tolerances of the peristaltic hoses
Data Source
Figure 1
AI summary
The present disclosure relates to a method for calibrating a pump, comprising the steps of providing a known volume of a liquid in a container; aspirating the known volume with a pump through a channel; determining with a liquid sensor the time for aspiration of the whole known volume by measuring liquid/air changes in the channel; comparing the determined time for aspiration with an expected time for aspiration; calculating at least one calibration value depending on a deviation from the expected time for calibration; applying the at least one calibration value to parameters for the aspiration process. A device is provided comprising a pump, a channel for receiving a liquid, a liquid sensor for measuring liquid air changes in the channel, wherein the liquid sensor is arranged next to the channel, and a controller which is connected to the liquid sensor for receiving its data, wherein the controller comprises a storage with stored data of aspiration processes considering liquid properties, hose dimensions and data form the pump and a calculator for comparing the data form the liquid sensor with stored data.