One-Step Laser Synthesis of Copper Nanoparticles and Laser-Induced Graphene in a Paper Substrate for Non-Enzymatic Glucose Sensing

The synergy resulting from the high conductivity of graphene and catalytic properties of metal nanoparticle has been a resource to improve the activity and functionality of electrochemical sensors. This work focuses on the simultaneous synthesis of copper nanoparticles (CuNPs) and laser-induced graphene (LIG) derived from paper, through a one-step laser processing approach. A chromatography paper substrate with drop-casted copper sulfate is used for the fabrication of this hybrid material, characterized in terms of its morphological, chemical, and conductive properties. Appealing conductive properties are achieved, with sheet resistance of 170 Ω sq⁻¹ being reached, while chemical characterization confirms the simultaneous synthesis of the conductive carbon electrode material and metallic copper nanostructures. Using optimized laser synthesis and patterning conditions, LIG/CuNPs-based working electrodes are fabricated within a three-electrode planar cell, and their electrochemical performance is assessed against pristine LIG electrodes, demonstrating good electron transfer kinetics appropriate for electrochemical sensing. The sensor's ability to detect glucose through a non-enzymatic route is optimized, to assure good sensing performance in standard samples and in artificial sweat complex matrix.