Method and apparatus for the determination of biomass in a suspension, such as a culture, in `real` time and a fermentation process using the method. In the method the electrical capacitance of the suspension is measured and from the measurement the volume fraction of the suspension enclosed by the cytoplasmic membranes of the cells (biovolume) is determined.
A fermentation controller correctly controls fermentation and produces a required material by fermentation. The fermentation controller (3) controls fermentation in a material production unit (1) that produces a material by fermentation. The controller (3) includes a capacitance sensor (63) to detect a capacitance change representative of a fermenting state in the material production unit and a memory (77) to store a reference capacitance change representative of a reference fermenting state. The controller compares the detected capacitance change with the reference capacitance change and controls fermentation in the material production unit according to the comparison result.
A method and apparatus for determining gas hold-up in a fermentation culture, in which, prior to aeration and during fermentation, a high frequency alternating signal is input to electrodes in electrical contact with the culture, the magnitude of the reactive current signal leading the voltage in the electrode circuit is determined and the difference in said magnitudes prior to aeration and during fermentation is used as a measure of the gas hold-up. The system may be combined with various methods of measuring biomass to give a gas hold-up corrected value of biomass.
The proposed method allows to determine by dielectrometry the variation of the glass-transition temperature (Tg) of a polymer material used in the presence of fluids (water/organic compound/gas), pure or in admixture. More precisely, the invention is based on the use of dielectric sensors whose geometry is such that they allow to follow, in a sensitive and reproducible way, the frequency and/or temperature dependence of the dielectric permittivity characteristics of a polymer material in the presence of fluids without disturbing permeation/desorption of the solute during transient and unsteady states, these dielectric measurements (real and/or imaginary part) being connected with the plasticized state of the material, which determines the performances thereof during use.
To detect a variation of capacitance in a path of a piping and enable to decide a fluid state of a fluid substance flowing through the path in the piping, a capacitance sensor (15) includes a measuring electrode (33) and a grounding electrode (35) made of a conductive metallic film and wound around a path in the piping (1), with an insulator (17) in between. A shield member (23) covers the measuring electrode and grounding electrode, with an insulator in between. The grounding electrode is narrower than the measuring electrode, and the measuring electrode and the grounding electrode are alternately disposed and are wound to be spiral along a flow direction.
A method and apparatus for investigating various parameters of biofluids, such as blood, particularly protein and cellular concentrations and cellular volume utilises the application of at least two a.c. frequencies, preferably simultaneously, in the range 0.1 to 60 MHz to a sample of the fluid and receiving and resolving the frequencies after passage through the fluid. The received frequencies are processed to derive corresponding d.c. voltage amplitudes which are mathematically processed to provide a numeric output correlating with a parameter under investigation, A new parameter named Instant Sedimentation Rate (ISR) is disclosed.
