3 May 2018 1.5mm precision liquid level measurement using impedance spectroscopy
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Abstract
An impedance measurement based level sensor is proposed using a co-axial probe for sensing liquid level in a container. The co-axial sensing probe is made with a hollow stainless steel outer conductor enclosing an insulated inner conductor. The impedance of the co-axial probe varies with the water level in a nonlinear fashion. The supporting electronics was developed using MSP 432 microcontroller unit (MCU) platform from Texas Instruments (TI) and a newly designed Impedance Analyzer-Analog Front End (IA-AFE) developed at TI. An inverter amplifier based circuit was implemented within the IA-AFE for impedance measurement. Discrete Fourier Transform (DFT) is calculated on the MCU platform from the sampled input and output square wave voltages of the IA-AFE. The proposed sensor shows a maximum error within ±1.5 mm, for the probe of length 40 cm. The proposed system offers an accurate and economical liquid level measurement platform outperforming the state-of-art level sensors to the best of our knowledge.
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Bhuwan Kashyap, Bhuwan Kashyap, Charles Sestok, Charles Sestok, Anand Dabak, Anand Dabak, Srinath Ramaswamy, Srinath Ramaswamy, Ratnesh Kumar, Ratnesh Kumar, } "1.5mm precision liquid level measurement using impedance spectroscopy", Proc. SPIE 10643, Autonomous Systems: Sensors, Vehicles, Security, and the Internet of Everything, 106430Y (3 May 2018); doi: 10.1117/12.2305014; https://doi.org/10.1117/12.2305014
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