In-Situ pH Sensor Calibration in Sterile Bioreactors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for calibrating pH sensors in sterile environments, such as bioreactors, are labor-intensive and prone to errors due to sterilization processes and temperature differentials, making it difficult to perform accurate primary calibrations and corrections without compromising sterility.
Innovation Solution
A method involving the introduction of a buffer and a gas mixture with variable CO2 concentrations into an enclosed vessel, where pH signals and CO2 concentrations are measured to generate calibration curves for both the buffer and the pH sensor, allowing for automatic calibration without sampling, using a controller to calculate and apply calibration parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pH sensors are calibrated by sampling and external measurement, then calibration can be performed, but sterility is compromised and labor intensity increases
Solution Approach 1:
The pH sensor performs self-calibration by measuring pH signals within the enclosed sterile vessel. The sensor calibrates itself against known buffer pH values without requiring external sampling or removal from the sterile environment, thereby maintaining sterility while reducing labor intensity.
Solution Approach 2:
The calibration function is extracted from the external sampling process and integrated directly into the enclosed vessel. By introducing buffers and measuring pH signals in-situ, the calibration process is separated from sterility-compromising external operations.
2Reliability
If sterilization processes are applied to calibration equipment, then sterility is maintained, but calibration accuracy decreases due to temperature differentials
Solution Approach 1:
Buffers are introduced into the enclosed vessel and allowed to equilibrate to the vessel's temperature before pH measurements are taken. This preliminary temperature equilibration eliminates temperature differential errors while maintaining sterility through the closed system.
Solution Approach 2:
The calibration process accounts for temperature variations by using temperature-compensated pH measurements. The system measures pH signals at the actual vessel temperature rather than at standard reference temperatures, and applies appropriate compensation to maintain accuracy.
3Adaptability or versatility
If manual calibration procedures are used, then flexibility is maintained, but productivity decreases and errors increase
Solution Approach 1:
The system automatically processes pH signals from multiple buffer measurements, compares them against known buffer pH values, and calculates calibration parameters through feedback loops. This automated feedback mechanism increases productivity and reduces human error while maintaining the flexibility to handle different buffer types and configurations.
Solution Approach 2:
Manual mechanical calibration operations are replaced with automated electronic measurements and calculations. The controller automatically introduces buffers, measures pH signals, processes data, and applies calibration parameters, eliminating manual labor while maintaining procedural flexibility through programmable sequences.
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
This approach enables precise and automated pH sensor calibration within sterile environments, reducing labor and minimizing errors associated with sterilization and temperature variations, while maintaining the integrity of the controlled conditions.
Implementation Method 1
measuring a pH signal of each solution with the pH sensor
Implementation Method 2
measuring a pH signal of each solution with the pH sensor and a CO2 concentration of a headspace gas of each solution
Implementation Method 3
sequentially introducing a gas mixture comprising CO2 into the enclosed vessel to form gas mixture and buffer solutions having variable concentrations of CO2
Data Source
AI summary
Methods of calibrating a pH sensor fixed within an enclosed vessel are disclosed. The methods include introducing a buffer into the enclosed vessel, introducing a gas mixture comprising CO2 into the enclosed vessel, measuring a pH signal of the solution, measuring a CO2 concentration of a headspace gas of the solution, and calculating a pH value with a buffer calibration curve. The methods include calculating a calibration parameter with a sensor calibration curve and calibrating the pH sensor with the calibration parameter. Reactor systems are also disclosed. The systems include an enclosed reactor, a pH sensor, a CO2 sensor, a temperature control subsystem, and a controller. Methods of facilitating pH sensor calibration without sampling in a bioreactor system are also disclosed. The methods include providing a controller and providing instructions to operably connect the controller to the pH sensor and the CO2 sensor.