Visible to the public Relative Permittivity Meter Using a Capacitive Sensor and an Oscillating Current Source

TitleRelative Permittivity Meter Using a Capacitive Sensor and an Oscillating Current Source
Publication TypeConference Paper
Year of Publication2019
Authorsde Almeida Arantes, Daniel, Borges da Silva, Luiz Eduardo, Teixeira, Carlos Eduardo, Campos, Mateus Mendes, Lambert-Torres, Germano, Bonaldi, Erik Leandro, de Lacerda de Oliveira, Levy Ely, da Costa, Germando Araújo
Conference NameIECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society
ISBN Number978-1-7281-4878-6
Keywordscalibration, Capacitance, capacitance measurement, capacitance measurements, capacitance meter, capacitance-selective behavior, capacitive sensor, capacitive sensors, Capacitors, composability, constant current sources, current source, dielectric constant, electronic circuit, fluid analysis, Fluids, Howland current source oscillation, industrial processes, measurement errors, Meters, Metrics, oscillating behaviors, Permittivity, permittivity measurement, physical properties, privacy, pubcrawl, real-time measurement, relative permittivity, relative permittivity meter, resilience, Resiliency, steady oscillating behavior, substance inspection, workbench LCR meter

The relative permittivity (also known as dielectric constant) is one of the physical properties that characterize a substance. The measurement of its magnitude can be useful in the analysis of several fluids, playing an important role in many industrial processes. This paper presents a method for measuring the relative permittivity of fluids, with the possibility of real-time monitoring. The method comprises the immersion of a capacitive sensor inside a tank or duct, in order to have the inspected substance as its dielectric. An electronic circuit is responsible for exciting this sensor, which will have its capacitance measured through a quick analysis of two analog signals outputted by the circuit. The developed capacitance meter presents a novel topology derived from the well-known Howland current source. One of its main advantages is the capacitance-selective behavior, which allows the system to overcome the effects of parasitic resistive and inductive elements on its readings. In addition to an adjustable current output that suits different impedance magnitudes, it exhibits a steady oscillating behavior, thus allowing continuous operation without any form of external control. This paper presents experimental results obtained from the proposed system and compares them to measurements made with proven and calibrated equipment. Two initial capacitance measurements performed with the system for evaluating the sensor's characteristics exhibited relative errors of approximately 0.07% and 0.53% in comparison to an accurate workbench LCR meter.

Citation Keyde_almeida_arantes_relative_2019