The development of the first single use probes produced for dielectric spectroscopy focused on a design that replicates the probes used in conventional cGMP production bioreactors. The electrode geometry and platinum material that is exposed to the cell culture in the single use probe is identical to geometry and material used in the robust 25mm diameter steam sterilizable probes with four flat, parallel flush electrodes typically used in the larger cGMP production bioreactors. These single us probes have been proven to be ideal for the larger single rocking motion bags and stirred tank bioreactors and are now commercially available. For the smaller bags, like those required in stem cell production, a different design was required and we describe the challenges of the probe scale down. Particular attention is given to the way electrode polarization was addressed on the new style of probe; the polarization is an artifact at lower measuring frequencies that increases as the electrode size is reduced.
The connecting dielectric spectroscopy electronics are also required to be assembled in a much smaller design space and again the poster shows how these were modified to connect to the small single use probes.