Precise speed control is enabling reliable results in a variety of medical industry bioreactor motion control applications. Knowing speed is set and regulated, within a tolerance of +/- 0.1 RPM for extended periods of time, assures consistent results in applications ranging from mixing liquids or pumping.
Bioprocess control stations
Bioprocess control stations are being designed as a universal platform capable of meeting the ever changing needs of all segments of the biotech and pharmaceutical sciences. Suitable for microbial to cell culture, scaling up to scale down and batch to fed-batch processing, new solutions has the right combination of features within an ultra-compact footprint.
Software solutions include the ability to control up to eight units from a single user interface, automatic gas mixing algorithms which simplify control (4-gas, 3-gas), along with O2 and N2 enrichment and a ten-point cascade feature which enables more sophisticated control strategies.
Bioreactor control systems are being loaded with features including easy to use graphical user interfaces (GUI). Systems offer the ability to monitor and control the pH, dissolved oxygen (DO), and temperature with PID control. Implementing a bioreactor motor/ temperature control algorithms enables real-time signals to control the mixer’s servo motor and turn the heater on or off under computer control.
New bench-top scale bioreactors are targeting both mammalian and microbial models. These units can seamlessly transition between auto-clavable and single-use bioreactors using a magnetic coupling drive that is fully contained, low maintenance and eliminates any contamination. A servomotor/drive is used to provide low friction magnetic-drive agitation suitable for cell culture & microbial upstream bioprocesses, and is also compatible with auto-clavable and single-use vessels.
Medical device manufacturers have been able to use Luminary servo drive technology from Industrial Indexing Systems (IIS) to easily configure these applications using a digital drive interface option.
The digital drive interface option bypasses the normal analog circuit path to allow access to the digital registers which control the operation of the speed control loop. Using the universal RS-485 device bus with Modbus RTU as its connectivity scheme, the digital drive is reachable from a variety of HMI, PLC and PC type controllers.
The drive’s speed control loop consists of a circuit to monitor and control the motor’s torque using a speed command as the input target value. In this control loop process, the speed of the motor shaft is measured on a periodic time-base and compared to the input target value. Any difference between the two values is applied as a correction to the torque control that is needed to accelerate or decelerate the motor shaft back to the desired speed. The shaft speed stays constant, within a small tolerance, due to the quick reaction time of the correction applied to the torque control loop.