New C4D Sensor with a Simulated Inductor

Abstract

A new capacitively coupled contactless conductivity detection (C4D) sensor with an improved simulated inductor is developed in this work. The improved simulated inductor is designed on the basis of the Riordan-type floating simulated inductor. With the improved simulated inductor, the negative influence of the coupling capacitances is overcome and the conductivity measurement is implemented by the series resonance principle. The conductivity measurement experiments are carried out in three pipes with different inner diameters of 3.0 mm, 4.6 mm and 6.4 mm, respectively. The experimental results show that the designs of the new C4D sensor and the improved simulated inductor are successful. The maximum relative error of the conductivity measurement is less than 5%. Compared with the C4D sensors using practical inductors, the measurement accuracy of the new C4D sensor is comparable. The research results also indicate that the adjustability of a simulated inductor can reduce the requirement for the AC source and guarantee the interchangeableness. Meanwhile, it is recommended that making the potential of one terminal of a simulated inductor stable is beneficial to the running stability. Furthermore, this work indirectly verifies the possibility and feasibility of the miniaturization of the C4D sensor by using the simulated inductor technique and lays a good foundation for future research work.

How Geometry Affects Sensitivity of a Differential Transformer for Contactless Characterization of Liquids

“…Although the concentration generally has a non-linear impact on the sample conductivity [41], it could be shown in [36] that the imaginary part of the output voltage US of the differential transformer depends linearly on the concentration within this narrow range. The sensitivity Sc is determined by using the imaginary part of the output voltage Im{US} at two different concentrations (e.g., c1 = 100 mmol/L and c2 = 150 mmol/L) according to Equation (2).…”

“…Since most of the electric field was concentrated in the foil, these results were not promising. However, there are systems like capacitively coupled contactless conductivity detection (C 4 D) [2], allowing for capacitive measure through a usually special fused-silica capillary with a small cross-section [3,4]. Nevertheless, due to the small cross-section of the capillary, C 4 D is not suitable for in-line measurements where higher fluxes of the medium is expected.…”

Contactless conductivity detection for analytical techniques— Developments from 2014 to 2016

“…The inductances required in this approach are relatively large, requiring bulky coils. For this reason the authors also investigated the use of a so‐called simulated inductor . This consists of an active circuitry, incorporating several operational amplifiers, which behaves like a large inductor and thus can be used as a substitute.…”

Bacterial Concentration Detection using a PCB-based Contactless Conductivity Sensor

“…Capacitively coupled contactless conductivity detection (C 4 D), by analyzing and testing the conductivity change of sample [34], could simply and sensitively detect metal cations, amino acids, and organic ions in beer, wine, milk, potable water, and juice [35,36,37,38]. The electrodes of C 4 D contain three electrodes, the excitation electrode to which AC signal is applied, the shield electrode, and the pick-up electrode, which measured the detection signal.…”