Many pharmaceutical manufacturers are adopting single-use manufacturing methods for a variety of reasons, but when they do existing equipment configurations and mounting methods often no longer work. This is the situation Brandon Haschke describes in his article posted on BioProcess Online, The Rise in Single-Use Instrumentation Options in Bioprocessing. Gleaming stainless steel equipment looks wonderful, but operationally the design constrains it to the original use case. Users want more flexibility, and single-use manufacturing methods can be a major advance to meet this goal.
The growing implementation of Single-Use manufacturing methods for upstream vessels and downstream processing equipment addresses these and other issues by providing options for scalability and operational savings, but it also introduces some new requirements. This is especially true with regards to how processes are instrumented and automated. Traditional automated measurement techniques are fixed-in-place just like the conventional equipment they are designed to be connected to, so the instruments and fittings must evolve for use with disposable Single-Use methods.
That sounds good, but what about instrumentation? When moving from fixed-asset stainless steel, how do you get the needed DO reading, or pressure or pH for that matter?
Single-Use bags are fabricated with pre-installed fittings and use materials compatible with the product and able to survive the gamma radiation sterilization procedure. It is also possible to install traditional DO and pressure sensors through standard fittings so they could contact the process, but this introduces difficulties for initial setup and calibration during operation. A more advantageous option is to use sensors based on traditional technologies but installed into specialized bag fittings that isolate the sensor from process product contact but still allow the measurement.
Some single-use bag manufacturers are already installing sensors and fittings into tube sets so readings can be taken when transferring product between production units. These do the job, but are only part of the picture. Brandon offers a whole list of considerations and requirements for sensors used in single-use service. Read the article and you’ll see what a major undertaking it has been for Emerson to create mounts and connections able to meet all the requirements. Take pressure for example
Pressure is the most straightforward process sensor that can be updated for SUT service. In fact, the sensor technology itself remains the same as for traditional sensors. The key is a disposable fitting manufactured into a Single-Use bag. This fitting features a flexible diaphragm which isolates the process fluid from the sensor element, while allowing the physical pressure to transfer to the sensor. This combination allows the sensor to be reused, lowering the consumables cost since only the fittings change from one batch to the next. The removable sensor is robust and highly accurate, and the fitting allows the sensors to be removed, replaced or recalibrated if required, even during a batch run.
In addition to pressure, Emerson offers specialized sensors for pH and DO. The pH sensor is Emerson’s Rosemount 550pH Single-Use Sensor, and it can operate for 30 days without any required maintenance or recalibration. For DO, Emerson’s Rosemount 550DW Single-Use Dissolved Oxygen Sensor Adapter can be placed into a bioreactor single-use bag to provide trouble free service.
You can find more information like this and meet with other people looking at the same kinds of situations in the Emerson Exchange365 community. It’s a place where you can communicate and exchange information with experts and peers in all sorts of industries around the world. Look for the Life Sciences Group and other specialty areas for suggestions and answers.