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  • Real time monitoring of viable yeast concentration in production fermenters using novel RF impedance probes

    Author: John Carvell, Robert Todd, Stephen Cunningham and Takeshi Yonezawa
    Publication date: 16-05-2001
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  • Recent Developments in Using Scanning Radio-Frequency Impedance Measurements on Cell Culture Processes

    Author: John P Carvell, Aditya Bhat, Pareshkumar M Patel, Gerard H Markx
    Publication date: 01/01/70
    Abstract
    The viable cell concentration is of prime importance in monitoring cell culture manufacturing processes. Of the available online biomass assays, the radio-frequency impedance (RFI) method has some clear advantages for manufacturing because it is an unambiguous reflection of viable cell biovolume rather than the total number of cells. This allows RFI to be used to control feeding rates or to maintain a constant level of biomass within the bioreactor. RFI is also suitable for measuring the live cell density in bioreactors when the cells are attached to microcarriers and to inert discs. Traditional RFI-based systems measure the capacitance at either one frequency (typically 0.5 MHz) or in a dual frequency mode. However, scanning the capacitance in a frequency range, typically between 0.1 and 20 MHz, also makes it possible to measure other important parameters such as the cell size, the cell membrane capacitance, and the cell interior conductivity online.3,4 Online measurement of such properties can provide useful information regarding the physiological state of the cells, which can assist in better understanding and controlling the fermentation or cell culture process. In this article, we introduce the concept, theory, and challenges of applying RFI frequency scanning using the Aber Biomass Monitor (Aberystwyth, UK) to cell culture processes, and show examples of how additional process parameters can be derived.
    Publication link
  • Recent Developments in Using Scanning Radio-Frequency Impedance Measurements on Cell Culture Processes

    Author: John P Carvell, Aditya Bhat, Pareshkumar M Patel, Gerard H Markx
    Publication date: 01/01/70
    Abstract
    The viable cell concentration is of prime importance in monitoring cell culture manufacturing processes. Of the available online biomass assays, the radio-frequency impedance (RFI) method has some clear advantages for manufacturing because it is an unambiguous reflection of viable cell biovolume rather than the total number of cells. This allows RFI to be used to control feeding rates or to maintain a constant level of biomass within the bioreactor. RFI is also suitable for measuring the live cell density in bioreactors when the cells are attached to microcarriers and to inert discs. Traditional RFI-based systems measure the capacitance at either one frequency (typically 0.5 MHz) or in a dual frequency mode. However, scanning the capacitance in a frequency range, typically between 0.1 and 20 MHz, also makes it possible to measure other important parameters such as the cell size, the cell membrane capacitance, and the cell interior conductivity online.3,4 Online measurement of such properties can provide useful information regarding the physiological state of the cells, which can assist in better understanding and controlling the fermentation or cell culture process. In this article, we introduce the concept, theory, and challenges of applying RFI frequency scanning using the Aber Biomass Monitor (Aberystwyth, UK) to cell culture processes, and show examples of how additional process parameters can be derived.
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  • New Applications and Methods Utilizing Radio-Frequency Impedance Measurements for Improving Yeast Management

    Author: John P. Carvell and K. Turner
    Publication date: 01-02-2003
    Abstract
    Radio-frequency (RF) impedance or capacitance measurements are used in many of the larger automated breweries for measuring viable yeast cell concentration. This paper reports the latest applications for this technique in the yeast pitching and yeast recovery lines and new on-line methods for monitoring live yeast cell concentrations during fermentation. The new methods include a range of probes that can be inserted into either a production propagator under highly aerated conditions or a production fermenter or it can be submerged into a vessel to monitor the yeast-concentration profile in real time. The paper also describes how the RF impedance measurement can be combined with a bulk fluorescence measurement to measure both live and dead yeast cell counts.
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  • Improved control of yeast pitching rate using the Aber Yeast Monitor – financial implications

    Author:
    Publication date: 01/01/70
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