Development of a Contactless Conductivity Sensor in Flowing Micro Systems for Cerium Nitrate

Abstract

Impedance spectroscopy has a high potential to detect chemical reactions in flowing systems. In this work, the approach using impedance spectroscopy as a possible analytical tool for a continuous hydrothermal syntheses (CHTS) is presented. With the CHTS-process, it is possible to produce metalloxide nanoparticles with a close particle size distribution and specific surface properties. For this, it is necessary to evaluate the electrode geometry, frequency and other factors influencing the impedance with respect to concentration measurements. In case of frequency-sweep measurements possible electrode geometries for C4D-Sensors (capacitively coupled contactless conductivity detection) are evaluated. Then distinguishability and reproducibility are tested applying titration measurements to show the ability for concentration detection in constant flow systems. The possibility to measure concentration changes in flowing systems in a reproducible and fast manner as well as with high distinguishability for the test solution cerium nitrate will be presented. Furthermore, the major influencing-factors like electrode geometry, frequency etc. could be determined. It has been shown that with increasing electrode spacing and electrode width, the distinguishability of the concentrations increases and shifts them to lower frequencies.

A New Contactless Cross-Correlation Velocity Measurement System for Gas–Liquid Two-Phase Flow

“…The CCD sensor shows great potential for use in the parameter measurement of gas–liquid two-phase flow in small channels [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. Unfortunately, when trying to combine the CCD sensor with the cross-correlation velocity measurement principle and apply it to the velocity measurement of gas–liquid two-phase flow in small channels, difficulties exist [ 13 , 14 , 15 ].…”