Sensors 2016, 16(11), 1900; https://doi.org/10.3390/s16111900
A Novel Application for Low Frequency Electrochemical Impedance Spectroscopy as an Online Process Monitoring Tool for Viable Cell Concentrations
Christoph Slouka 1,4,*
, David J. Wurm 1, Georg Brunauer 2
, Andreas Welzl-Wachter 3, Oliver Spadiut 1,4, Jürgen Fleig 3 and Christoph Herwig 1,4
, Andreas Welzl-Wachter 3, Oliver Spadiut 1,4, Jürgen Fleig 3 and Christoph Herwig 1,41
Research Division Biochemical Engineering, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria
2
Institute for Energy Systems and Thermodynamics, Vienna University of Technology, Vienna 1060, Austria
3
Research Division Electrochemistry, Institute of Chemical Technology and Analytics, Vienna University of Technology, Vienna 1060, Austria
4
Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria
*
Author to whom correspondence should be addressed.
Academic Editor: Alexander Star
Received: 9 September 2016 / Revised: 29 October 2016 / Accepted: 9 November 2016 / Published: 11 November 2016
(This article belongs to the Section Biosensors)
Abstract
New approaches in process monitoring during industrial fermentations are not only limited to classical pH, dO2 and offgas analysis, but use different in situ and online sensors based on different physical principles to determine biomass, product quality, lysis and far more. One of the very important approaches is the in situ accessibility of viable cell concentration (VCC). This knowledge provides increased efficiency in monitoring and controlling strategies during cultivations. Electrochemical impedance spectroscopy—EIS—is used to monitor biomass in a fermentation of E. coli BL21(DE3), producing a recombinant protein using a fed batch-based approach. Increases in the double layer capacitance (Cdl), determined at frequencies below 1 kHz, are proportional to the increase of biomass in the batch and fed batch phase, monitored in offline and online modes for different cultivations. A good correlation of Cdl with cell density is found and in order to get an appropriate verification of this method, different state-of-the-art biomass measurements are performed and compared. Since measurements in this frequency range are largely determined by the double layer region between the electrode and media, rather minor interferences with process parameters (aeration, stirring) are to be expected. It is shown that impedance spectroscopy at low frequencies is a powerful tool for cultivation monitoring. View Full-Text
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Slouka, C.; Wurm, D.J.; Brunauer, G.; Welzl-Wachter, A.; Spadiut, O.; Fleig, J.; Herwig, C. A Novel Application for Low Frequency Electrochemical Impedance Spectroscopy as an Online Process Monitoring Tool for Viable Cell Concentrations. Sensors 2016, 16, 1900.
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