Based on the PD nature of your application, and your preference for a single use sensing solution, I would recommend you take a look at the CITSens Bio Process Probe from C-CIT Sensors. It is available in several variations including a high glucose, low glucose or combination of glucose and lactate. As with your pH and DO sensors, the C-CIT offering fits into a standard PG 13.5 thread on your bioreactor headplate and is available in the 120MM or 225mm sensor length you require.

CITSens Bio Process Probe