A flexible self-healing sweat sensor based on co single atom/conductive polymer hydrogel for uric acid detection

In this work, we have developed a flexible electrochemical sensor for the detection of uric acid based on Co single-atom catalyst (Co-N-C)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)-polyvinyl alcohol (PEDOT:PSS-PVA) conductive polymer hydrogel. The flexible sensor can tackle mechanical damage through dynamic bonds in the Co-N-C/PEDOT:PSS-PVA hydrogel that enable rapid self-healing, restoring conductivity and integrity after deformation. Taking advantage of the excellent electrical conductivity of conductive polymer PEDOT:PSS and the high catalytic activity of Co-N-C, the flexible sensor exhibits a broad linear range of 1-2000 μM with low limit of detection of 0.16 μM (S/N = 3) for uric acid. In addition, the sensor displays excellent anti-interference performance and repeatability (relative standard deviation of 1.0%). Benefiting from the abundant dynamic reversible bond interactions in the Co-N-C/PEDOT:PSS-PVA hydrogel network, the sensor demonstrates over 90% recovery of its electrochemical current response after 5 self-healing cycles, exhibiting its exceptional self-healing capability. In applying the sensor to detecting uric acid in real-life sweat samples, the results positively correlate with those obtained using enzyme-linked immunosorbent assay, validating its reliability in practical applications. This work presents a strategy for developing a flexible and self-healing sensor to detect uric acid in sweat.