Disposable Pump Calibration for Fluid Mixing Accuracy

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Solution Overview

Problem

Disposable fluid processing systems in biopharmaceutical production face challenges in achieving accurate fluid mixing due to the lower accuracy and time stability of pumps with disposable wetted parts, such as peristaltic pumps, which require frequent calibration and are prone to drift, and the limited precision of disposable flow meters that avoid pre-calibration to prevent contamination.

Innovation Solution

A method for conveying a mixture of fluids in a disposable fluid processing system using at least one flow meter and two pumps, where each pump is calibrated by pumping a calibration fluid volume at various speeds, registering flow rates, and calculating pump calibration functions to achieve accurate mixing, with the option to simulate back pressure using a throttle valve and employ multivariate analysis for complex cases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If disposable pumps with disposable wetted parts (e.g., peristaltic pumps) are used to reduce sanitation and validation costs, then ease of manufacture and sanitation are improved, but manufacturing precision and time stability deteriorate due to lower accuracy and drift with time

Engineering Contradiction:

Improvesanitation and validationVSAvoidflow rate accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The system performs preliminary calibration of disposable pumps by measuring actual flow rates against target flow rates before use, storing calibration factors that compensate for manufacturing variations and drift, thereby maintaining precision while using disposable components

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously measures actual flow rates using flow meters and adjusts pump operation in real-time based on feedback from measured versus target flow rates, compensating for drift and maintaining accuracy throughout operation

Inventive Principle:

Principle #23Feedback

2Reliability

If disposable flow meters are used without pre-calibration to avoid contamination, then reliability is improved, but measurement precision deteriorates due to limited accuracy

Engineering Contradiction:

Improvecontamination avoidanceVSAvoidflow rate accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system uses flow meters to continuously measure actual flow rates and provides feedback to the control system, which adjusts pump operation to compensate for measurement limitations and achieve target flow rates with higher precision

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system changes operational parameters (pump speed, pulse width modulation) based on measured flow rates to optimize mixing accuracy, using the flow meter data to dynamically adjust system parameters rather than relying on fixed pre-calibration

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If peristaltic pumps are used in disposable systems, then ease of operation is improved, but reliability deteriorates due to drift with time from tubing movement during operation

Engineering Contradiction:

Improvedisposable system operationVSAvoidtime stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system continuously monitors flow rates and adjusts pump operation in real-time to compensate for drift caused by tubing movement, maintaining reliable and accurate flow delivery throughout the operation period

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary calibration to establish baseline characteristics of the disposable pump and tubing combination, storing calibration factors that account for expected drift patterns and enable compensation during operation

Inventive Principle:

Principle #10Preliminary action

4Manufacturing precision

If traditional piston pumps are used to achieve high precision and accuracy in flow rates, then manufacturing precision is improved, but ease of manufacture deteriorates due to requirement for sanitation and validation between batches

Engineering Contradiction:

Improveflow rate control accuracyVSAvoidsanitation and validation complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The system replaces expensive, sanitation-intensive traditional piston pumps with disposable pumps that have disposable wetted parts, eliminating the need for complex sanitation and validation procedures while maintaining acceptable precision through calibration and feedback control

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS10589239B2Fluid mixing in a disposable fluid processing system

Publication Date: 2020.03.17 CYTIVA SWEDEN AB

AI summary

High accuracy mixing of fluids in a disposable fluid processing system with at least two pumps is provided by a method where a calibration fluid volume is pumped through each pump via a flow meter at at least one calibration pump speed while registering the flow rate using data output from the flow meter, a pump calibration function is calculated from the calibration pump speed and flow rate data and two or more operation fluids are mixed to a predetermined mixture ratio and predetermined flow rate by controlling the pump speed of the respective pumps in accordance with the pump calibration functions.