Abstract: A method is provided for calibrating impedance-spectroscopic biomass sensors that are embodied to detect information regarding the quantity and/or size of living cells in a biomass by means of an electric field having a periodically changing field direction A calibration suspension encompasses an electrically conductive viscously flowable or viscoelastic carrier substance and electrically conductive solid particles and/or solid semiconductor particles received therein. An electric field is generated having a periodically changing field direction, which acts on the calibration suspension. At least one permittivity value is detected, respectively representing a permittivity of the calibration suspension, in a context of at least two electric fields having different field direction change frequencies. A difference value is ascertained that represents a difference between the detected permittivity values. The difference value is compared with a reference value associated with the calibration suspension.

Abstract: A pH combination electrode includes inner and outer tubes, working and reference electrodes, and a hydrogel diaphragm between the tubes. A seal is disposed inside the inner tube closer to a first inner tube end than to the second inner tube end. An extended reference chamber is formed inside the inner tube between the seal and the second inner tube end. A first conductive fluid is contained in the inner tube between the seal and the first inner tube end. A second conductive fluid is contained in the extended reference chamber and in a reference chamber formed between the inner and outer tubes. A through-hole in the inner tube allows the second conductive fluid to flow between the reference chamber and the extended reference chamber. The working electrode extends into the inner tube, through the seal and into the first conductive fluid. The reference electrode contacts the second conductive fluid.

Abstract: A combination electrode includes a working electrode, a reference electrode, a hydrogel diaphragm, an outer tube and an inner tube. The working electrode is disposed in the inner tube. The reference electrode is disposed in a reference chamber formed between the inner tube and the outer tube. The hydrogel diaphragm seals the opening between an end of the outer tube and the inner tube when the hydrogel swells upon coming in contact with a first electrically conductive fluid that is introduced into the reference chamber. The diaphragm is coupled to the reference electrode in an electrically conductive manner through the first electrically conductive fluid, which contacts both the reference electrode and the diaphragm. The inner tube is closed by a glass membrane that is coupled to the working electrode in an electrically conductive manner through a second electrically conductive fluid that contacts both the glass membrane and the working electrode.

Abstract: A method is provided for calibrating impedance-spectroscopic biomass sensors that are embodied to detect information regarding the quantity and/or size of living cells in a biomass by means of an electric field having a periodically changing field direction A calibration suspension encompasses an electrically conductive viscously flowable or viscoelastic carrier substance and electrically conductive solid particles and/or solid semiconductor particles received therein. An electric field is generated having a periodically changing field direction, which acts on the calibration suspension. At least one permittivity value is detected, respectively representing a permittivity of the calibration suspension, in a context of at least two electric fields having different field direction change frequencies. A difference value is ascertained that represents a difference between the detected permittivity values. The difference value is compared with a reference value associated with the calibration suspension.

Abstract: A polymer compound according to the invention comprises an acrylic acid copolymer composed of acrylic acid derivatives and/or methacrylic acid derivatives, containing: a) at least one acrylic acid derivative and/or methacrylic acid derivative substituted with a sulfonic acid group; b) at least one hydrophilically substituted acrylic acid derivative and/or methacrylic acid derivative; c) at least one lipophilically substituted acrylic acid derivative and/or methacrylic acid derivative; and d) at least one acrylic acid derivative and/or methacrylic acid derivative which acts as a crosslinking agent.