Precision pH Sensor Based on WO3 Nanofiber-Polymer Composites and Differential Amplification

Seon Jin Choi, Suchol Savagatrup, Yoonseob Kim, Jeffrey H. Lang, Timothy M. Swager

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


We report a new type of potentiometric pH sensor with sensitivity exceeding the theoretical Nernstian behavior (-59.1 mV/pH). For the pH-sensitive electrode, 1D tungsten oxide (WO3) nanofibers (NFs) were prepared to obtain large surface area and high porosity. These NFs were then stabilized in a reactive porous chloromethylated triptycene poly(ether sulfone) (Cl-TPES) binder, to facilitate proton diffusion into the polymer membrane. The measurements were performed with a differential amplifier using matched MOSFETs and providing a 10-fold amplified signal over a simple potentiometric determination. A high pH sensitivity of -377.5 mV/pH and a linearity of 0.9847 were achieved over the pH range of 6.90-8.94. Improved signal-to-noise ratios with large EMF signal changes of 175 mV were obtained in artificial seawater ranging pH 8.07-7.64 (ΔpH = 0.43), which demonstrates a practical application for pH monitoring in ocean environments.

Original languageEnglish (US)
Pages (from-to)2593-2598
Number of pages6
JournalACS Sensors
Issue number10
StatePublished - Oct 25 2019
Externally publishedYes


  • WO nanofiber
  • differential amplifier
  • pH sensor
  • porous polymer

ASJC Scopus subject areas

  • Bioengineering
  • Instrumentation
  • Process Chemistry and Technology
  • Fluid Flow and Transfer Processes


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