Whether pH, dissolved oxygen, conductivity, viable cell density or redox, while analog sensors have been the product of choice in many areas and still are, modern intelligent sensors offer a range of advantages.
Sensor technology has continuously improved over the last years. The sensor market has changed a lot since the FDA initiated the PAT (Process Analytical Technology) initiative, challenging the pharmaceutical industry to adopt quality innovations through real-time monitoring and control of their processes. While the initiative has indeed spurred valuable new technologies, the journey to a complete quality-by-design future is still in its early stages, with monitoring of many critical process parameters (CPPs) showing room for progress.
While analog sensors have been, and still are, the product of choice in many areas, modern intelligent sensors offer a range of advantages that enable users to comply with the PAT framework. They demand in-line process sensors that allow for automated control of critical process parameters instead of documenting them by means of manual sampling and separate analytical devices. Intelligent sensors can communicate directly with the process control system (PCS) without the need for a separate transmitter. They not only send a compensating measurement value to process control but also a variety of diagnosis data that are automatically recorded and stored in the sensor.
The data recording and transmission are further designed to not only comply with, but also to surpass, the FDA and GMP requirements. Hamilton, for example, offers intelligent sensor technology under the brand name “Arc”. This covers their complete range of pH, dissolved oxygen, conductivity, viable cell density and redox sensors, together with their “Arc Air” app, a comprehensive software that configures, calibrates, validates and troubleshoots these sensors.
Artificial Intelligence and Self-Diagnostics
The technology offers the advantage of an off-line calibration under defined conditions. Furthermore, configuration settings can easily be transferred to other sensors, which drastically reduces both the time requirement for employees and the error potential. Due to the Modbus communication, operators are able to fully use the comprehensive data from these smart sensors. It is also a two-way communication, so the sensor can be configured directly from the PCS without the need for a transmitter.
Possible sensor problems are detected immediately and not only at the end of a process. In case of an error, this feature can help to save an entire charge. The smart Arc sensors send alarms, information for debugging, quality indicators and diagnosis to the process control system as well as wirelessly to the Arc Air app that can be run on mobile devices. The data recording and transmission are designed to meet or exceed FDA and GMP regulatory guidelines. This way, the operator is able to see instantly when the sensor was used, and if calibration or interface errors or other warnings occurred. Arc Air also records possible hardware errors such as glass impedance. The information can be used immediately, as in the case of process deviations, or for future decisions, such as when to calibrate or replace the sensor.
Despite all of these advances, there are always hurdles to overcome. PAT encourages more and more data acquisition, and technology will need to continue to advance in order for operators to acquire, maintain, and use this influx of data (see expert interview below).
* The author is Marketing Communication Manager at Hamilton Bonaduz AG, Switzerland.