Biostat® RM and Flexsafe® RM Bags

Contact Specialist

Biostat® RM and Flexsafe® RM Bags

The Biostat® RM (Rocking Motion), is a fully GMP compliant, wave-mixed bioreactor. It is used with single-use Flexsafe® RM bags which are proven for a broad range of different cell lines incl. CHO, NS0, SF9, E.coli, stem cells and CAR-T cells. Depending on your individual process needs and working volumes you can choose from a variety of system and bag configurations.

Biostat® RM Top Features

  • Industry proven and established in commercial production processes
  • No slip agents and optimized antioxidant package for excellent cell growth of also sensitive cell lines
  • Available with BioPAT® Viamass SU biomass measurement
  • Flexsafe® RM Bags are designed for Biostat® RM Rockers; basic Flexsafe® Bags are also compatible to third party rockers / wave systems

  • Stand alone rocker with gassing module and optional load cells
  • For more capabilities – system also available with Biostat® B control tower: enables sophisticated process control, features e.g. online biomass measurement (BioPAT® Viamass) and perfusion set up
  • Biostat® B control tower configuration - Twin option for reduced footprint

  • Biostat® B with RM 200 for working volumes up to 100L
  • Bag-integrated cell retention filter for intensified seed or production processes
  • For super easy and cost efficient cultivation with increased productivity
  • Seamless integration into higher level SCADA systems and GMP environments


Regenerative Medicine

Regenerative Medicine therapeutics repair, replace and engineer human cells, tissues and organs to restore their normal function. The discipline has great potential to address clinical needs that are currently unmet by conventional pharma or biopharmaceutical products. Rocking motion bioreactors are widely used for the expansion step during stem and T-cell cultivation processes, incl. CAR-T. Companies are actively approaching us to work on the integration of our rocking motion bioreactors into their process environment and explore the PAT capabilities coming with our single-use systems. Tests that these customers perform with Flexsafe® RM bags continue to be successful, also for the most sensitive cells.


Wave based single-use bioreactor technology is a well established and proven, yet cost effective method to establish a fully single-use seed train. Different process modes can be flexibly applied to increase cell numbers for subsequent inoculation of larger scale bioreactors. Especially perfusion cultivations appear to be capable of even replacing an n-x stirred tank seed reactor.


Sartorius technologies are ideally suited for the production of viral vaccines, vectors and gene therapies. They allow end-to-end, single-use processing of viruses from process development through to commercial manufacturing at the 2000 L-scale in stirred tank reactors. Rocking motion bioreactors are frequently applied in seed cultivation steps, but also as production bioreactors as the technology is comparably cheap and easy to use.

Sartorius Stedim Biotech provides single-use technologies and associated services to address the process development and productions needs of vaccine manufacturers.

Seed Train

The Biostat® RM is used in seed train in many commercial manufacturing sites worldwide. Bags are cost efficient and easy to handle. Tube diameters of the Flexsafe® RM bags are designed to fit the larger Flexsafe STR® stirred bioreactor bags and Flexsafe media storage bags. Benefit from the same film in you manufacturing platform and minimize the validation efforts.

Discover the Biostat® RM

Innovative Technology for Your Process Needs

Biostat® RM 20 | 50 basic is a perfectly sized, single-use, wave-mixed benchtop bioreactor for stand-alone use. It features an exchangeable bag holder to fit bags with a total volume of 1 – 50 L. The Biostat® RM Basic rocking platform with an integrated local controller, Air | CO2 mixing module and optional load cells is the optimal choice for straight-forward applications, such as seed generation.

The Biostat® B is our universal benchtop controller for stirred and rocking motion systems. It is available with the RM Rocker for advanced process control featuring pH, DO and BioPAT® Viamass. The system is fully configurable and can therefore serve various process needs, from process development to small scale commercial production.

Biostat® B with RM 200 Rocker is your choice for production-scale seed expansion and rapid material supply for preclinical and clinical studies using proven rocking motion technology. The bag holder fits the Flexsafe® RM bags in a working volume range from 10 up to 100 L.

The wave generated in the RM bags due to the rocking motion ensures effective gas exchange through the gas-liquid interface. Four different gas lines for air, O2, N2 and CO2 are equipped with flow meters and four high-precision mass flow controllers. An integrated pressure sensor continuously measures the pressure inside the bag. To ensure process safety, aeration is switched off when an upper threshold is reached.

The Flexsafe® RM bags are available in 1 L, 2 L, 10 L, 20 L, 50 L, 100 L and 200 L size. Bags are available in basic, optical and in two different perfusion configurations.

Basic bags are designed for use in seed train and production applications without pH and DO control. Optical bags feature integrated single-use opto-chemical pH and DO sensors, which are already pre-calibrated. Used together with the Biostat® RM control tower, they allow high end cultivation with full process automation. Basic and optical bags up to 50 L size are also available with screw caps (38 mm diameter). The screw cap can be used for the insertion | removal of larger objects inside a laminar flow cabinet, e.g. microcarriers. Perfusion bags are available in two versions: A) With an integrated 1.2 μm perfusion membrane (PES). The membrane is fixed at the bottom of the bag, forming a compartment for removal of cell free media. The wave created by the agitation moves over the surface of the membrane, thereby flushing the membrane with every rocking motion. This innovative and patented design ensures low fouling and long cultivation times. B) ATF perfusion bags are designed for the convenient connection to an external cell retention device via OPTA connector.

Flexsafe® RM Bags are supplied gamma irradiated and ready to use. The Flexsafe® RM bag is mounted on the bag holder of the rocker easily and secured on both sides through fixation clamps.

Precise and reliable single-use sensors for pH and DO come pre-installed and sterilized with the bag. The sensors are pre-calibrated and the calibration data is supplied together with the bag (for pH and DO). 10 to 200 L bags are also available with integrated sensors for measurement of viable biomass (BioPAT® Viamass). All 2nd generation Biostat® B with RM systems can be equipped with the BioPAT® Viamass electronics.

BioPAT® Viamass - viable biomass measurement

BioPAT® MFCS – Software for reliable data acquisition, monitoring and control

Extractables and Leachables Testing

Ensuring Safe Adoption of Single-Use Systems in Biopharmaceuticals.

Learn More


CountryPatent number


US 6,673,532 B2

US 7,041,493 B2

US 8,304,231 B2

US 6,673,532 B2

US 9,017,997 B2 


EP 1 309 719 B1

EP 1 778 828 B1

EP 2 268 788 B1

EP 2 945 978 B1

EP 2 945 801 B1







Contact a Specialist