A flow through coaxial cell to investigate high frequency broadband complex permittivity: Design, calibration and validation

•New apparatus: a large coaxial cell with a flow through system for high frequency broadband dielectric spectroscopy.•Calibration based on a single measurement made on reference liquid (deionized water)•Computation of complex permittivity performed based on iterative solver or optimization method using a frequency dependent model of the complex permittivity.•High performance obtained for the determination of the real part of the complex permittivity and good performance for the determination of the imaginary part of the complex permittivity. This paper presents a new apparatus: a large flow through coaxial cell designed for broadband dielectric characterization of material under controlled hydraulic and chemical boundaries. The cell is calibrated with a single measurement made on a perfectly known dielectric liquid (deionized water) together with an optimization procedure. Then, two methods are proposed to compute the dielectric characteristics: an iterative solver and an optimization method. These two methods are systematically investigated for two reference liquids: a low loss dielectric material (ethylene glycol) and high loss dielectric liquid (saline solutions with different concentration). Tabulated data were used to perform a quantitative error analysis in terms of estimated complex permittivity. The results have shown high performance in terms of real part and good performance in terms of real part. The measurements on saline solution also highlight the impact of electrode polarization with dramatic effect in the lower part of the frequency range.