Recent advances in fabrication of smart dressings for real-time monitoring of pH in chronic wounds-a review

Healing of wound involves a complex series of events in four overlapping phases, namely hemostasis, inflammation, proliferation, and remodeling. Non-healing or hard-to-heal wounds usually get stuck in inflammation phase. These categories of wounds are prone to infect via bacterial activities and biofilm formation. To avoid this, timely detection of infection is very important for proper management of wound and effective treatment. This could be achieved through continuous monitoring of pH in wound milieu. While the pH of intact skin is mostly in acidic region (4-6), this is turned to alkaline conditions (7-9) for chronic wounds. Recently, flexible optical and electrochemical pH sensors have been developed for this purpose, which are integrated in medical dressings and could be used as wearable products in medical field. Whenever designing a pH sensor, the most important factors, which should be considered, include biocompatibility, sensitivity, response time, accuracy and precision, storage life, reproducibility, photochemical stability, and cost. In this review, a relatively comprehensive study of the research conducted for design and fabrication of various optical and electrochemical pH sensors during the last five years has been presented.