Novel Textile Wearable Sensor for Uric Acid Monitoring in Wound Exudate

A major cause for the development of severe and/or chronic wounds is to be found in certain pathologies such as immunodeficiencies, diabetes, compression traumas in bedridden people and diabetes. Nowadays, wound health assessment is performed by removing the bandages and visually inspecting the injury, i.e. an operation that presents an intrinsic risk of infection and disturbance of the healing processes. Instead, for these afflictions it would be crucial to have a continuous and real-time insight regarding the wound health status, which provides the medical personnel with the ability to deliver targeted therapies, leading to a better and faster patient recovery. To address these issues, our research group has recently developed new devices to non-invasively monitor pH and moisture in wound exudate, as these two biomarkers are strongly correlated with wound health status. In this work we showcase a novel textile sensor base on an organic electrochemical transistor (OECT) architecture based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) for uric acid (UA) monitoring in wound exudate, as UA levels can be correlated to infective and necrotic processes during the wound healing phases. This sensor is produced using special medical grade textile materials that provide a passive sampling system, enabling the continuous, real-time and non-invasive analysis of wound exudate to monitor wound health status. The devices are made by screen-printing a PEDOT:PSS-based conductive ink on medical gauzes, while the electrical connections are assembled by sewing conductive textile threads. UA was quantified 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 to reversibly respond 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).