Flexural Fatigue Testing of Bioprocess Bags
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Solution Overview
Problem
Current flexural fatigue testing methods for polymer film-based bags used in rocking bioreactors are time-consuming, labor-intensive, and do not effectively mimic the creases and dimples formed on the bags, leading to inadequate evaluation of fatigue resistance, especially under extreme conditions.
Innovation Solution
A system and method that simulate the creases and dimples on polymer films using a rocking bioreactor platform with increased rocking rates and extreme geometries, allowing for rapid and reproducible testing of flexural fatigue resistance by inducing controlled indentations and cyclic stress on the films, enabling faster failure analysis and comparison of different film compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rocker test is used to test flexural fatigue resistance of polymer films in bioreactors, then the test can generate realistic dimples and creases on the bags, but the testing process becomes time-consuming, labor-intensive, and low throughput
Solution Approach 1:
The patent creates a simplified copy of the realistic crease geometry observed in rocker tests using a predetermined indentation tool. Instead of performing the complex, time-consuming rocker test to generate creases, the invention directly reproduces the essential crease geometry through controlled indentation, achieving the same testing objective with much higher throughput and automation capability
Solution Approach 2:
The patent extracts the essential feature from the complex rocker test process - the crease geometry itself - and separates it from the time-consuming rocking motion. By using a predetermined indentation tool to directly create the crease pattern, the invention removes the labor-intensive rocking step while retaining the critical crease formation needed for fatigue testing
2Reliability
If the rocker test runs for extended periods to achieve film failure, then comprehensive fatigue resistance data is obtained, but the testing duration increases to days or months
Solution Approach 1:
The patent applies preliminary action by pre-forming the indentation/crease geometry before the fatigue cycling begins. This preliminary crease creation concentrates the stress at the critical location from the start, eliminating the need for extended testing periods to naturally develop creases through prolonged rocking, thus accelerating the time to failure while maintaining data reliability
Solution Approach 2:
The patent changes the testing parameters by using a predetermined indentation geometry that concentrates stress more effectively than natural creases. This parameter change in the stress distribution pattern accelerates the fatigue process, reducing testing duration from days/months to hours while still providing comprehensive fatigue resistance data
3Ease of manufacture
If standard flexural fatigue testing methods are used, then the testing protocol is simple, but the methods cannot effectively mimic the creases and dimples formed on cell culture bags in rocking bioreactors
Solution Approach 1:
The patent introduces an intermediary element - the predetermined indentation tool - that bridges the gap between simple testing protocols and realistic crease formation. This intermediary device directly creates the necessary crease geometry without requiring complex rocking machinery, maintaining protocol simplicity while achieving accurate crease mimicry for reliable fatigue testing
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 accelerates the flexural fatigue testing process from days to hours, allowing for rapid pre-screening and quality control of film lots, facilitating the selection of suitable films for bioprocess applications by simulating the cyclic folding and stress conditions of rocking bioreactors, thereby improving the robustness of cell cultures.
Implementation Method 1
the continuous imposition of cyclic stresses due to the rocking motion of the bioreactor... can lead to flexural fatigue of the polymer film
Implementation Method 2
contacting the folded edge of the film with an indenter to create an indentation having a depth or a radius of curvature, or a combination thereof, on the mounted film
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
Disclosed herein are methods and systems for rapid testing of films used in the manufacture of bioprocess bags. The methods described herein allow for determination of resistance to flexural fatigue while mimicking actual conditions in bioprocesses such as flexion and subsequent fatigue and failure of a bioprocess bag made of a film when it is placed on a rocking platform shown for example in Figure 1.