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Language: English

Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received September 5, 2012
Accepted December 6, 2012

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Slow drift modeling and compensation in the glass electrode dynamics for the fast measurement of pH

Seungjae Lee Wonhui Cho¹ Jietae Lee^2†

Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD21264, U.S.A., USA ¹enGibbs, A-503 Shin Young Gwell Estates, Bansong-dong, 93-10, Hwasung, Gyeonggi 445-160, Korea ²Department of Chemical Engineering, Kyungpook National University, Daegu 702-701, Korea

jtlee@knu.ac.kr

Korean Journal of Chemical Engineering, May 2013, 30(5), 1008-1012(5), 10.1007/s11814-012-0214-x

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Abstract

Glass electrodes for measuring pH in solutions show relatively fast responses with slow drifts. To design compensators to remove the drifts that hinder fast measurements of pH, a dynamic model that consists of ordinary and partial differential equations is proposed. It can explain such two-time scale responses of glass electrodes. The fitting accuracies of the proposed model are experimentally evaluated in frequency-domain and time-domain. The frequency responses obtained from the square wave responses show the fitting abilities of the proposed model, and the step responses also support this. The step responses filtered based on the proposed model show that pH measurements can be made considerably faster. The proposed model can be used to improve the dynamics of glass pH electrodes by compensating dynamic elements causing slow drifts.

Keywords

Glass Electrode pH Sensor Slow Sensor Drift Identification Dynamic Compensation

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