A low-cost flexible pH sensor array for wound assessment

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 micro electrodes 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/AgClreference 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 (r(2) = 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. (c) 2016 Published by Elsevier B.V.