Modelling of non-steady-state concentration profiles at ISFET-based coulometric sensor-actuator systems

W. Olthuis, J. Luo, B.H. van der Schoot, P. Bergveld, M. Bos, W.E. van der Linden

    Research output: Contribution to journalArticleAcademicpeer-review

    22 Citations (Scopus)
    105 Downloads (Pure)

    Abstract

    Acid or base concentrations can be determined very rapidly by performing an acid—base titration with coulometrically generated OH− or H+ ions at a noble metal actuator electrode in close proximity to the pH-sensitive gate of an ion-sensitive field effect transistor (ISFET). The ISFET is used as the indicator electrode to detect the equivalence point in the titration curve. Typical values for the time needed to reach the equivalence point are 0.5–10 s for acid or base concentrations ranging from 0.5 × 10−3 to 20 × 10−3 mol l−1. A model is presented, giving an analytical description of the diffusion phenomena that occur with the sensor—actuator system. The results of this analytical model description, using linearized concentration gradients, are presented together with the results of numerical simulations. Both results are in good agreement with measurements.
    Original languageEnglish
    Pages (from-to)71-81
    Number of pages11
    JournalAnalytica chimica acta
    Volume229
    Issue number11
    DOIs
    Publication statusPublished - 1990

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