Local pH measurement with scanning ion conductance microscopy

Celeste A. Morris, Chiao Chen Chen, Takashi Ito, Lane A. Baker

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


We report microscale pH probes and their application as a scanning probe in Scanning Ion Conductance Microscopy (SICM). Experiments are performed with electrodes that consist of a thin gold layer deposited on one side of a nanopipet. Subsequent insulation of the electrode with parylene and electropolymerization of aniline to form a polyaniline (PANi) thin film on the gold electrode surface creates a microscale pH probe with a dynamic range of pH 2.5-12 and sensitivity of 0.02 ΔpH. Porous membranes were examined with prepared electrodes. Ion current measured at the nanopipet opening served to control the position of the electrode with respect to themembrane surface and to report local conductance in the vicinity of the nanopipet, while local pH wasmeasured by recording the potential difference between the PANi electrode and a reference electrode. Application of a transmembrane potential difference was utilized for additional control over migration across the membrane. Lateral resolution of the EMF response was studied with micrometer diameter pores. Additionally, the vertical resolution of the EMF response was studied as the pipet was lowered into the pores where a ΔpH of 0.13 was measured.

Original languageEnglish
Pages (from-to)H430-H435
JournalJournal of the Electrochemical Society
Issue number8
Publication statusPublished - 2013 May 7

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry


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