Simple-structured hydrophilic sensors for sweat uric acid detection with laser-engraved polyimide electrodes and cellulose paper substrates

Abstract

Accurate detection of uric acid (UA) is crucial for diagnosing gout, yet traditional sweat-based UA sensors continue to face challenges posed by complex and costly electrode fabrication methods, as well as weakly hydrophilic substrates. Here, we designed and developed simple, low-cost, and hydrophilic sweat UA detection sensors constructed by carbon electrodes and cellulose paper substrates. The carbon electrodes were made by carbonized polyimide films through a simple, one-step laser engraving method. Our electrodes are porous, possess a large specific surface area, and are flexible and conductive. The substrates were composed of highly hydrophilic cellulose paper that can effectively collect, store, and transport sweat. The constructed electrodes demonstrate high sensitivity of 0.4 µA L µmol−1 cm−2, wide linear range of 2–100 µmol/L. In addition, our electrodes demonstrate high selectivity, excellent reproducibility, high flexibility, and outstanding stability against mechanical bending, temperature variations, and extended storage periods. Furthermore, our sensors have been proven to provide reliable results when detecting UA levels in real sweat and on real human skin. We envision that these sensors hold enormous potential for use in the prognosis, diagnosis, and treatment of gout.