Model‐based accuracy enhancements for guarded conductivity measurements: determination of effective electrode areas utilising numerical field simulation

Abstract

Methods utilising current measurements for conductivity and permittivity determination require precise knowledge of the effective electrode area in order to obtain accurate results. Owing to field distortions (e.g. caused by fringing) in guarded electrode setups, the effective electrode area differs significantly from the geometrical calculated. Focusing on guarded electrode setups for conductivity determination, a generic method based on numerical field simulation is presented allowing a convenient determination of the relevant effective electrode area. For this purpose, a brief overview of yet existing normative guidelines and related research work is provided. State-of-the-art conductivity measurement setups are presented in order to identify parameters which affect the field distribution within the measurement arrangements. The description of the implemented method and its realisation in COMSOL multiphysics is followed by its validation using analytical fringing calculations. Furthermore, presented method is used for the evaluation of fringing effects and additional field distortion caused by design aspects of the measurement cell itself and potential imbalances related to the measurement setup. Moreover, dependencies on conductivity of the surrounding environment are considered. Achieved model-based accuracy enhancements are calculated and are leading to a gain in precision for conductivity determination of up to 25% compared to yet existing approaches.

Surface‐modification effect of MgO nanoparticles on the electrical properties of polypropylene nanocomposite

“…DC volume resistivity was measured by a pico‐ammeter (Keithley 2635B, USA) and a three‐electrode system at 30°C [30]. The film sample with a thickness of 100 μm was sputtering‐coated with gold electrodes, and the electric field is controlled as 35 kV/mm.…”

Non‐contact method to reduce contact problems between sample and electrode in dielectric measurements

“…At the boundary of the electrode, the electrostatic flux that is partly through the sample and partly through the air will still have an effect both on the amplitude and the phase of the complex capacitance. It is shown in [24] that for the measurement cell design, involved materials, potential distribution and the test specimen height are factors that influence the fringing. For the four‐electrode arrangement illustrated above, the fringing should be assessed considering those aspects.…”