Accurate complex permittivity measurement with two-electrode contact-free apparatus

Abstract

A novel methodology for deducing the complex permittivity of a sample from capacitance and loss measurements of a non-contacting two-electrode (unguarded) arrangement is presented. This methodology and its practical implementation introduced here as the ratio reference method tackle the issue of sample-dependent electric field distortions viewed in prior art, such as the air reference method, as a fundamental challenge of achieving high-accuracy measurements of permittivity in an absolute sense with contact-free configurations. Computer modelling is used to comprehensively demonstrate the method's practical implementation and its general applicability to achieve a raw accuracy to within a few percent for a wide range of complex permittivity directly from capacitance and loss measurements. Characterization of the raw accuracy and utilizing it for compensation are also posited and demonstrated with an example to improve this accuracy by an order of magnitude.