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Rütten Softmixer

 

 

 

Rütten Engineering Softmixers® are ideal, low shear force agitators to support the cultivation of cells in suspension or on micro-carriers in laboratory scale, pilot and production environments supporting vessel volumes of 50 to 300 litres and up to 5'000 litres, respectively. Scaling-up is simple: Mixing plates of various sizes can be used to obtain the same mixing conditions as in laboratory units. In addition, two or more mixing plates can be employed with large vessels. The broad operating flexibility of the Softmixer® coupled with advanced, application-specific software enables an extraordinarily efficient and gentle convection-like current within the medium. Rütten Engineering also supplies air and oxygen microsparging systems whose filter surfaces remain free of cell deposits during long cultivation processes.

Softmixer Mixing Plates

 

 

Linear motor

 

 

 

 

Quick-connect coupling

 

 

Sterile seal

 

 

 

 

 

Softmixer Mixing Plate

 

 

© Purpose

Bioreactors used today for cultivating living cells are frequently equipped with radial or axial impellers. Both radial and axial impellers induce high shear forces into the liquid and, even if driven at low speed, can create detrimental conditions for critical substances such as living cells or micro-carriers. Furthermore, the tangential forces generated by the fast rotation of either type of impeller cause the formation of vortices. The Rütten Softmixer® has been developed to avoid all these shortcomings.

© Solution

The Rütten Softmixer® offers unprecedented capabilities in shear sensitive mixing situations. the Softmixer®  is capable of mixing by slow gentle strokes or rapid reciprocating oscillations of a centrally mounted mixing plate. The oscillation frequency of the Softmixer® can range from 0.1...6 Hz. The amplitude of the mixing plate can be adjusted from 0.5...60 mm. the mixing plate is perforated with conical holes that gently surge the fluid as the plate moves thereby creating gentle and highly effective mixing throughout the vessel (see schematic on page Laboratory Softmixer® ). Variations in drive and mixing plates are possible for a large spectrum of applications up to 5'000 litres. Power transmission into the vessel is by a shaft sealed with a silicone bellow, absolutely assuring sterility. A microprocessor control allows adaptation of the Softmixer®  to each individual need. When coupled in a feedback loop to the Mixmeter®  the Softmixer®  can provide exquisite control of mixing in a multitude of applications.

© Modernization of older cell cultivation systems

Laboratory-, Pilot- and Production Softmixers® can successfully replace traditional stirring systems in existing cell cultivation systems. The vessels should have spherical or dished bottoms. Rütten Engineering supports the customer during a retrofit. The change is simple: All Softmixers® are delivered as connection-ready, autonomous units. The Softmixer® control system can function as an independent unit or be coupled to existing process systems.

© Components

The Softmixer® contains mainly of the following components:

The Linear Motor mounted on a stainless-steel support and equipped with a quick-connect coupling to facilitate motor removal during vessel autoclave sterilisation.

The Bellows Seal made of FDA compliant silicone to ensure system sterility.

The Oscillating Mixing Plate with conical holes generates a gentle fluid flow.

The Control Electronic and PC Workstation. The Control electronic consists of the motor control, the power supply and an alarm system. It is connected to the computer via the RS232 serial interface. The PC workstation is configured with a 1.5 GHz Intel Pentium 4 processor, 128 MB RAM, a 20 GB hard disk, a TFT monitor and Windows 98 software* (*subject to change).

The Softmixer® Control Program. The program controls linear motor movements such as start/stop, initialisation, amplitude and frequency are displayed over time (mixing signal display optional). The software also supports a batch mode, batch program editing, and syntax checking

© Your benefits

Unprecedented low shear force agitator.

Mixing plate suitable for covering a wide range of applications.

Best possibilities for controlling the frequency, amplitude and energy transmitted to the mixing plates.

Can be sterilised in situ or autoclaved, no dead-spaces, easy to clean.

Capacities from 10 to 5000 litres, perfect to up-scale.

Precise mixing control when used with the Rütten Mixmeter®.

Rütten Engineering also supplies air and oxygen microsparging systems whose filter surfaces remain free of cell deposits during long cultivation processes.

The Softmixer® can also be mounted on existing bioreactors.

© References

The Rütten Softmixer® has been intensively tested on its function by the Queens University in Canada. Download the Acrobat Reader file and films at "Download".

 

General Data Laboratory Softmixer® Pilot Softmixer® Production Softmixer®
Mixing plate Diameter
No. of  holes
Vessel size
88,5mm
36
5
...20 l
148 mm
36
20
...200 l
570 mm
390
200
...5'000 l
Operating data Max. frequency
Min. freq
uency
Max. stroke
Min. stroke
8 Hz
0.1 Hz
30 mm
1 mm
6 Hz
0.1 Hz
60 mm
1 mm
6 Hz
0.1 Hz
100 mm
1 mm
Linear Motor Peak force
Weight
33 N
5 kg
204 N
9 kg
2'000 N
22 kg
Controller Size 544x199x395 mm 690x650x1640 mm 690x650 x1'640 mm

Schematic representation of a laboratory bioreactor with continuous harvesting and cell retention.

Laboratory Softmixer®

© Solution

Laboratory Softmixers® are ideal tools for the small-scale cultivation of living cells and can be adapted easily to many traditionally stirred laboratory bioreactors with volumes from 5 to 20 litres. The mechanical components of the existing stirring mechanism must be removed and replaced with the Rütten Softmixer®  unit. This operation is simple, and Rütten Engineering supports the customer with all the necessary hardware, including a new cover plate tailored for each reactor.

© Example with aeration circulation

1 Laboratory Softmixer linear motor

2 Softmixer mixing plate

3 Cell retention system

4 Harvesting tube

5 Transfer pump

6 Product recycling with glass wall surface aeration

7 Harvesting tank

8 Scale

SSS vessel 100 l with Pilot Softmixer®

Pilotsoftmixer® and Productionsoftmixer®

© Solution

Rütten Engineering Softmixers® are ideal, low shear force stirrers to support the cultivation of cells in suspension or on micro-carriers in pilot and production environments supporting vessel volumes of 50 to 300 litres and up to 5'000 litres, respectively. Scaling-up is simple: Mixing plates of various sizes can be used to obtain the same mixing conditions as in laboratory units. In addition, two or more mixing plates can be employed with large vessels. The broad operating flexibility of the Softmixer® coupled with advanced, application-specific software enables an extraordinarily efficient and gentle convection-like current within the medium.

© 2004 Copyright Rütten Engineering AG, Stäfa, Switzerland