Photometric Sensing of Active Chlorine, Total Chlorine, and pH on a Microfluidic Chip for Online Swimming Pool Monitoring

Sait Elmas, Aneta Pospisilova, Aneta Anna Sekulska, Vasil Vasilev, Thomas Nann, Stephen Thornton, Craig Priest

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    9 Citations (Scopus)
    11 Downloads (Pure)


    A microfluidic sensor was studied for the photometric detection of active chlorine, total chlorine, and pH in swimming pool samples. The sensor consisted of a four-layer borosilicate glass chip, containing a microchannel network and a 2.2 mm path length, 1.7 μL optical cell. The chip was optimised to measure the bleaching of methyl orange and spectral changes in phenol red for quantitative chlorine (active and total) and pH measurements that were suited to swimming pool monitoring. Reagent consumption (60 μL per measurement) was minimised to allow for maintenance-free operation over a nominal summer season (3 months) with minimal waste. The chip was tested using samples from 12 domestic, public, and commercial swimming pools (indoor and outdoor), with results that compare favourably with commercial products (test strips and the N,N’-diethyl-p-phenylenediamine (DPD) method), precision pH electrodes, and iodometric titration.

    Original languageEnglish
    Article number3099
    Number of pages13
    JournalSensors (Basel, Switzerland)
    Issue number11
    Publication statusPublished - 30 May 2020

    Bibliographical note

    © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (


    • active chlorine
    • microfluidic
    • online
    • pH
    • photometric
    • swimming pool
    • Chloramines
    • sensors
    • Chlorine
    • Microfluidic
    • Swimming pool
    • Photometric
    • Online


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