Adjustable Mixer Shaft for Sterile Bioreactor Pouches

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Bioreactors with large-volume flexible pouches face challenges in thorough mixing and storage due to the inflexible mixer shaft, which cannot be adjusted in length without opening the sterile pouch, complicating transport, storage, and sterilization processes.

Innovation Solution

A length-adjustable mixer shaft subdivided into shaft elements with a hollow member and a filler member, connected by resilient elements like rings for torque transmission and sealing, allowing adjustment within the pouch without opening it, and equipped with a duct for pressure equalization to prevent fluid ingress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the mixer shaft is made as a single rigid piece, then the mixing function is reliable, but the storage and transport volume increases significantly

Engineering Contradiction:

Improvemixing functionVSAvoidstorage and transport volume

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The mixer shaft is divided into multiple shaft elements (first shaft element, second shaft element, etc.) that can be connected in series. Each shaft element has a manageable length that fits within standard packaging, yet when assembled they form a sufficiently long shaft for effective mixing in large-volume bioreactors.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shaft elements are designed with hollow members and filler members that nest within each other during storage and transport. The second shaft element can be inserted into the first shaft element, creating a compact nested configuration that minimizes storage volume while maintaining the capability to form a long shaft when needed.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Volume of moving object

If the mixer shaft is assembled from multiple parts before sterilization, then the storage volume is reduced, but the sterile envelope must be opened compromising sterility

Engineering Contradiction:

Improvestorage volumeVSAvoidsterility

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The shaft elements are pre-assembled and pre-sterilized as complete units before being placed in the sterile pouch. This preliminary assembly and sterilization of components allows them to be introduced into the sterile environment as ready-to-use modules, eliminating the need to open the sterile envelope during assembly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The resilient element serves as an intermediary component that connects shaft elements while maintaining the sterile barrier. It allows mechanical connection and torque transmission between shaft elements without requiring penetration of the sterile pouch envelope, thus preserving sterility while enabling assembly.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If the mixer shaft length is fixed, then the manufacturing is simple, but the adaptability to different bioreactor volumes is reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidadaptability to different bioreactor volumes

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The mixer shaft transitions from a static fixed-length design to a dynamic adjustable-length design. The shaft elements can be connected in different configurations (one element, two elements, or more) depending on the bioreactor volume, allowing the same basic component set to adapt to various application requirements while maintaining manufacturing simplicity through standardized elements.

Inventive Principle:

Principle #15Dynamics

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

Enables flexible and efficient mixing and storage by allowing the mixer shaft to be easily adjusted in length within the pouch, reducing storage and transport issues and preventing contamination during sterilization, while avoiding the need for metallic locking mechanisms.

Implementation Method 1

on rotation of the mixer shaft the at least one resilient element transmits torque between the hollow member of the first shaft element and the filler member of the second shaft element

Methodology Applied

Scientific EffectTorque transmission: Torque

Implementation Method 2

A further function of the at least one resilient element consists in sealing off the cavity in the interior of the mixer shaft against fluids from the interior of the pouch

Methodology Applied

Scientific EffectSealing:

Implementation Method 3

the cavity in the interior of the mixer shaft being connected to the interior of the pouch by a duct which allows pressure equalization

Methodology Applied

Scientific EffectPressure equalization: Pressure Gradient

Data Source

PatentUS8870443B2Flexible pouch with a mixing apparatus

Publication Date: 2014.10.28 SARTORIUS STEDIM BIOTECH GMBH

AI summary

A flexible pouch has a mixing apparatus, the mixer shaft of which is adjustable in length for use as a bioreactor for culturing microorganisms and cells.