Bioprocess monitoring is moving rapidly beyond process sensors for dissolved oxygen (DO), pH, glucose, and carbon dioxide. Development groups and vendors are now coupling those critical measurements to more complex quality attributes, and ultimately to feedback control, as part of process analytic technology (PAT) initiatives. Ultimately, these techniques will lead to a top-down quality by design (QbD) approach to manufacturing.
“The idea of PAT is to have more and more data measured online,” says Gernot John, Ph.D., of PreSens Precision Sensing. “In the past the process was a black box, where at the end you analyze the product to assure the quality of the process.”
Online measurement, Dr. John explains, enables not only process control but ongoing process improvement. This differs from fixed processes that were “not touched” during production. “We are not there yet, but at some point we will be.”
PreSens manufactures chemical-optical sensors for oxygen, carbon dioxide, and pH. The first two devices are suitable for both stainless steel and single-use equipment; the pH sensor is used overwhelmingly in disposable equipment because “the classical pH sensor is more suited for multiple usage" for fixed-tank reactors. PreSens also supplies sensing-data transmitters and complete monitoring systems that include two or more sensors or probes.