Iridium oxide and cobalt hydroxide microfluidic-based potentiometric pH sensor

Weiyu Xiao, Qiuchen Dong*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Microliter volume pH determination is of great importance in the biomedical and industrial applications. The current available pH meter and measurement techniques are hard to reach the high demand of microliter volume pH determination in a repeatable, stable, and sensitivity manner. This work aims to fill the gap of microliter volume pH measurements while maintaining good sensing performance. The electrodeposited iridium oxide and cobalt hydroxide along with gold electrode served as working, counter, and reference electrode, respectively, for 10–12 μL volume pH measurements with Nernst constant of 55.9 ± 4.4 mV/pH. The electrodeposited thin film was further characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Raman spectrometry, etc. to confirm its morphology and composition. The constructed pH sensor was used for human serum sample measurements to confirm the suitability of future applications. The results show that it has only 0.80% variation compared to a commercial pH meter with a limit of detection (LOD, or resolution) of ± 0.01 pH. It holds a great potential to be used in the future for microliter volume in situ pH measurements. Graphical Abstract: [Figure not available: see fulltext.].

Original languageEnglish
Article number457
JournalMicrochimica Acta
Issue number11
Publication statusPublished - 2 Nov 2023


  • Cobalt hydroxide
  • Iridium oxide
  • Nernst constant
  • pH sensor
  • Potentiometric sensor


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