The practice of integrating bags, tubing, and filters into preassembled, ready-to-use bioprocess solutions is optimized if noninvasive sensing of critical process parameters is part of the package. These single-use assemblies frequently require treatment for bio-burden reduction or sterilization by nonthermal methods such as gamma irradiation because of the incompatibility of most bioprocess bag materials with temperatures associated with sterilization.
The benefits of single-use technology, including its ability to focus internal resources on core activities versus ancillary tasks such as cleaning validation and the expenses associated with that activity, have been well publicized. With all of the benefits that disposable technologies offer, performance—especially the monitoring and control of process conditions—must not be sacrificed.
Critical process parameters that are often monitored include pressure, pH, dissolved oxygen, conductivity, UV absorbance, flow, and turbidity. The packages that contain the traditional technologies for monitoring these parameters are not usually compatible with or effective when integrated into single-use assemblies for many reasons: cost, cross contamination, inability to maintain a closed system, and system incompatibility with gamma irradiation.
Even though these obstacles do not always preclude the use of traditional measurement technologies, single-use solutions for monitoring process parameters eliminate the need for equipment cleaning and autoclaving small parts, reduce the risk and cost involved with making process connections, and may be more cost effective than tracking and maintaining traditional technologies. For example, a sanitary, autoclavable pressure transducer that is qualified for a certain number of autoclave cycles and requires recalibration may be more expensive to use versus a single-use pressure sensor.
As single-use sensing technologies evolve, a framework for evaluation before implementation must be determined. Key points to consider are material properties, sensor manufacturing, process compatibility, performance requirements, control system integration, compatibility with treatments before use, and regulatory requirements.