Through the past decade, single-use bioreactors for culturing mammalian and insect cells have been widely adopted in preclinical, clinical, and production-scale biopharmaceutical facilities (1, 2). With such bioreactors in operation, monitoring and control of process parameters is vital for ensuring critical quality attributes (CQAs) of biologicals or vaccines are met for production of a safe product. Traditionally, bag-based and bench-top vessels have been fitted with conventional pH and dissolved oxygen (DO) probes similar to those used in stainless steel or…