Smart Dressing for Wound Health Monitoring

Certain pathologies such as diabetes, immunodeficiencies, skin grafts, compression traumas in bedridden people or third-degree burns are a major cause for severe and/or chronic wounds. In such conditions, a constant wound health status monitoring is critical to provide the medical personnel with the capability to tailor better targeted therapies, leading to an improved and faster patient recovery. At the moment wound health assessment is performed by removing the bandages and visually inspecting the injury, thus posing a risk of infection and disturbance of the healing stages. Recently, new devices have been developed by our research group to address these issues by monitoring pH and moisture in wound exudate, since these two biomarkers are strongly correlated to the wound health status. In this contribution we present a novel textile chemical sensor exploiting an organic electrochemical transistor (OECT) configuration based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) for uric acid (UA) selective monitoring in wound exudate. The medical-grade textile materials chosen for the device production provide a passive sampling system, enabling the continuous, real-time, and non-invasive analysis of wound exudate to monitor wound health status, as UA concentration is another important biomarker associated with infections or necrotization processes in human tissues. The devices are made by screen-printing a conductive ink based on PEDOT:PSS on medical gauzes, while the electrical connections are produced by sewing conductive textile threads. UA quantifications were performed by means of potentiostatic electrochemical techniques both in phosphate buffer solutions (PBS) and synthetic wound exudate (SWE) while operating in flow conditions using a HPLC pump at a flow rate of 0.05 mL/min to simulate the natural wound fluid emission. The sensors here developed proved to be capable of reversibly responding to variations in UA concentration within the biological range of interest for wound exudate (220 – 750 µM), displaying a normalized current response equal to a 47% signal variation per 10-fold increase in UA concentration (R2 = 0.98). The values obtained in PBS and SWE were found to be statistically comparable, as confirmed by a t-test (P = 0.95).