Printed composite electrodes for in-situ wound pH monitoring

New technologies are essential for intelligent wound management and to provide tools that facilitate a greater understanding of wounds and healing physiology. pH is an important marker for many processes in the wound environment; it cannot be fully utilised due to the inherent lack of suitable technologies currently available. The development and proof-of-concept testing for an electrochemical system that exploits pad-printed carbon-uric acid composite electrodes is detailed. Uric acid is incorporated to act as a biologically-safe pH probe within in the sensor assembly that can be manipulated to offer a simple voltammetric response. The development of the composite sensors, the activation of the basal carbon, and the surface deposition of 1,2-diaminobenzene to prevent biofouling are detailed. The prototype sensing assembly is shown to enable the interference-free measurement of pH (and linear quantification of endogenous uric acid) even in the presence of high ascorbic acid concentrations. The experimental developments culminate in a standard deviation of 0.164 for 20 replicates performed in simulated wound fluid, and sensitive monitoring of pH across a wide analytical range (pH 4-10) in simulated wound fluid. These findings suggest that printed carbon-uric acid composites may offer a novel, cheap and reliable mechanism for simple pH measurements at wound surfaces, a potentially powerful tool with clinical utility for wound management and one that may enable a greater understanding of pH implications on wound physiology, and the effects of dressings and treatments.