Bioreactor Phase Transition Control via Oxygen Supply
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Solution Overview
Problem
Existing bioreactor controllers face challenges in achieving reproducibility and consistency between batches due to inadequate transition between phases, such as batch and production phases, leading to inaccuracy and variability in process conditions.
Innovation Solution
A method is introduced that uses a relationship between an oxygen supply parameter and a dissolved oxygen value to effectively transition between phases, with the oxygen supply parameter determined by agitation speed, gas supply rate, and oxygen supply concentration, allowing for more responsive control and increased operational range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-input single-output (SISO) control loops are used for each process condition, then control of individual parameters (temperature, dissolved oxygen, pH) is achieved, but reproducibility and consistency between batches are poor
Solution Approach 1:
The patent combines multiple SISO control loops into a unified control system that manages transitions between batch and production phases. The controller integrates control of temperature, dissolved oxygen, and pH into a coordinated system that operates differently according to the current phase, thereby improving batch-to-batch consistency while maintaining manageable complexity through modular phase-based logic.
Solution Approach 2:
The control system dynamically adapts its behavior based on the current phase (batch or production). During batch phase, it optimizes for cell growth with appropriate setpoints; during production phase, it transitions to optimize for product formation with different setpoints. This dynamic adaptation improves reproducibility by ensuring each phase receives optimal control tailored to its specific requirements.
2Manufacturing precision
If existing bioreactor controllers are used, then basic process control is maintained, but optimal transition between batch phase and production phase cannot be achieved
Solution Approach 1:
The controller continuously monitors process conditions and prepares for phase transition in advance by detecting when conditions approach transition thresholds. It preemptively adjusts control parameters and setpoints before the actual phase change occurs, ensuring smooth and accurate transitions without delay. This preliminary action eliminates the lag inherent in existing controllers that react rather than anticipate phase changes.
Solution Approach 2:
The system employs continuous feedback monitoring of process conditions (dissolved oxygen, agitation rate, flow rate) to detect the optimal moment for phase transition. Based on this feedback, the controller automatically adjusts control signals to achieve precise transitions between batch and production phases, improving manufacturing precision while reducing transition delay time through real-time adaptation.
3Ease of operation
If delayed phase transitioning control is used, then simpler control logic is maintained, but inappropriate process condition setpoints are applied during transition period
Solution Approach 1:
The control system dynamically switches between batch-phase optimized setpoints and production-phase optimized setpoints based on real-time detection of phase transition conditions. During the brief transition period, the controller interpolates or smoothly switches between setpoints to ensure continuous optimal control. This dynamic approach maintains ease of operation through automated phase detection while preventing yield loss by avoiding inappropriate setpoint application.
4Extent of automation
If automated phase transition control is implemented, then manual intervention is reduced, but control accuracy and variability reduction require sophisticated algorithms
Solution Approach 1:
The automated control system uses continuous feedback from process sensors (dissolved oxygen, agitation rate, flow rate) to detect phase transitions and adjust control parameters. The feedback loop compares actual conditions with target conditions and automatically modifies control signals to maintain accuracy. This feedback mechanism enables high-level automation while achieving the manufacturing precision required for consistent batch-to-batch reproduction through real-time correction of deviations.
Data Source
AI summary
There is provided a method of controlling operation of a fed batch process in a bioreactor vessel, comprising transitioning from a batch phase to a production phase in dependence on a relationship between an oxygen supply parameter O and a dissolved oxygen value DO.