A copper oxide-modified laser-induced graphene electrode for the non-enzymatic and simultaneous detection of glucose and creatinine

Dual Cu(I)/Cu(II)/Cu(III) redox states in Cu 2 O/CuO-modified laser-induced graphene enable simultaneous, non-enzymatic detection of glucose and creatinine with high selectivity and stability. • Simple, scalable flash oxidation yields stable Cu 2 O/CuO nanoparticles on LIG. • Copper oxide-modified laser-induced graphene enables dual-analyte detection. • Distinct redox states of copper drive selective glucose and creatinine sensing. • Simultaneous, non-enzymatic detection without cross-interference. • Sensor shows low detection limits, high reproducibility, and long-term stability. Non-enzymatic biosensors are promising alternatives to enzyme-based sensors for personalized health monitoring because they offer lower cost, improved stability, and simpler fabrication. Nevertheless, their practical use remains limited by insufficient sensitivity, selectivity, and long-term stability, highlighting the need for robust and highly functional nanomaterial-based sensing platforms. In this study, we developed a laser-induced graphene (LIG) electrode modified with copper oxide (Cu x O, comprising coexisting Cu 2 O and CuO phases) for use in non-enzymatic biosensing applications. Systematic surface analysis confirmed the successful formation of Cu x O on the LIG structure. The incorporation of Cu x O nanoparticles significantly increased the surface area of the electrode, providing abundant active sites and enhancing its electrochemical properties. Owing to the unique redox mechanism of Cu x O, the sensor was able to selectively and sensitively detect both glucose and creatinine. The Cu x O-LIG sensor exhibited sensitive detection for glucose and creatinine within the ranges of 0–5.5 mM and 0–0.5 mM, with limits of detection of 84 μM and 5.4 μM, respectively. Moreover, well-separated oxidation potentials for glucose (0.65 V) and creatinine (0.04 V), enabled simultaneous detection. These results demonstrate the potential of the Cu x O–LIG platform as a robust non-enzymatic biosensor for multi-biomarker monitoring in healthcare applications.