A low-cost and accurate interface for conductivity sensors

Author

Li, Xiujun ; Meijer, Gerard C M

Author_Institution

Fac. of Inf. Technol. & Syst., Delft Univ. of Technol., Netherlands

Volume

1

fYear

2002

fDate

6/24/1905 12:00:00 AM

Firstpage

765

Abstract

This paper presents a low-cost and accurate interface for four-electrode conductivity sensors. The interface mainly consists of an analog front-end, a multiplexer and a voltage-to-time converter. The analog front-end is used to provide a controlled excitation voltage signal for the sensor and to convert the sensor signal (conductivity) into a voltage signal. The voltage-to-time period converter acts as an asynchronous converter for the sensor signals (voltage) employing a relaxation oscillator which output is a period-modulated signal. Experimental results over a conductance range of 0.1 μS to 20 mS show a random error of 0.32 μS and a systematic error of 1.32 μS for a measurement time of 400 ms.

Keywords

convertors; electric admittance measurement; electric sensing devices; electrical conductivity measurement; 0.1 muS to 20 mS; analog frontend; asynchronous converter; conductance measurement; contact potentials; controlled excitation voltage signal; four-electrode conductivity sensors; four-wire measurement method; low-cost accurate interface; multiplexer; nonidealities; operational amplifiers; period-modulated signal; random error; relaxation oscillator; voltage-time converter; Biomedical measurements; Conductivity measurement; Current measurement; Electrical resistance measurement; Electrodes; Impedance; Pollution measurement; Sensor systems; Voltage; Voltage-controlled oscillators;

fLanguage

English

Publisher

ieee

Conference_Titel

Instrumentation and Measurement Technology Conference, 2002. IMTC/2002. Proceedings of the 19th IEEE

ISSN

1091-5281

Print_ISBN

0-7803-7218-2

Type

conf

DOI

10.1109/IMTC.2002.1006938

Filename

1006938