Polymeric membrane ion-selective electrodes (ISEs) are a powerful tool for ion sensing. However, their application in complicated environmental water samples is still a challenge owing to the occurrence of electrode biofouling. To address this issue, we propose a facile and effective method for enhancing the anti-biofouling properties of these sensors. A self-adhesive coating based on waterborne polyurethane and biocide 4,5-dichloro-2-