A low-cost flexible pH sensor array for wound assessment

Rahim Rahimi, Manuel Ochoa, Tejasvi Parupudi, Xin Zhao, Iman K. Yazdi, Mehmet R. Dokmeci, Ali Tamayol, Ali Khademhosseini, Babak Ziaie

Research output: Journal article publicationJournal articleAcademic researchpeer-review

139 Citations (Scopus)


The pH level in a chronic wound bed is a key indicative parameter for assessment of the healing progress. Due to fragility and inability to measure multiple wound regions simultaneously, commercial glass microelectrodes are not well-suited for spatial mapping of the wound pH. To address this issue, we present an inexpensive flexible array of pH sensors fabricated on a polymer-coated commercial paper (palette paper). Each sensor consists of two screen-printed electrodes, an Ag/AgCl reference electrode and a carbon electrode coated with a conductive proton-selective polymeric (polyaniline, PANI) membrane. Laser-machining is used to create a self-aligned passivation layer with access holes that is bonded over the sensing and reference electrodes by lamination technology. Characterization of the pH sensors reveal a linear (r2= 0.9734) relationship between the output voltage and pH in the 4-10 pH range with an average sensitivity of -50 mV/pH. The sensors feature a rise and fall time of 12 and 36 s for a pH swing of 8-6-8. The sensor biocompatibility is confirmed with human kertinocyte cells.
Original languageEnglish
Pages (from-to)609-617
Number of pages9
JournalSensors and Actuators, B: Chemical
Publication statusPublished - 28 Jun 2016
Externally publishedYes


  • Chronic wound
  • Laser micromachining
  • Paper substrates
  • pH sensing array
  • Rapid prototyping

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry
  • Electrical and Electronic Engineering


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