Reference-electrode free pH sensing using impedance spectroscopy

Laura Folkertsma, Lennart Gehrenkemper, Jan Eijkel, Karin Gerritsen, Mathieu Odijk

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    We present a reference-electrode free sensor able to measure both pH and conductivity based on impedance spectroscopy. The electrode is made of a layer of indium-tin-oxide (ITO). The impedance of this electrode at low frequencies depends on its double layer capacity, which varies with pH due to modification of oxide groups at the ITO surface. At high frequencies, the impedance is determined by the resistance in the system, which corresponds to the inverse conductivity of the solution. Because no reference electrode is needed for this technique, miniaturization of the pH sensor is simple. We demonstrate a proof-of-principle experiment of the sensor for human plasma pH measurements.
    Original languageEnglish
    Title of host publicationEurosensors 2019
    Subtitle of host publicationProceedings MDPI
    Number of pages5
    Publication statusPublished - 30 Nov 2018
    Event32nd European Conference on Solid-State Transducers, Eurosensors XXXII 2018 - Graz, Austria
    Duration: 9 Sep 201812 Sep 2018
    Conference number: 32

    Publication series

    NameProceedings (MDPI)
    PublisherMultidisciplinary Digital Publishing Institute
    ISSN (Print)2504-3900


    Conference32nd European Conference on Solid-State Transducers, Eurosensors XXXII 2018
    Abbreviated titleEurosensors
    Internet address


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