MOF-Functionalized 455 nm Laser-Induced Graphene Flexible Electrode for Electrochemical Sensing

Electrochemical biosensors require electrode materials that are scalable, affordable, and effective for detecting target analyte. Laser-induced graphene (LIG) has emerged as a promising electrode material, yet traditional fabrication methods using expensive CO$_{2}$lasers limit accessibility. In this work, we report a low-cost and scalable fabrication strategy for flexible LIG electrodes using direct laser writing with a 10 W, 455 nm diode laser. While bare LIG offers excellent conductivity and porosity, it lacks specific binding sites for target molecules, resulting in limited sensitivity. Surface functionalization with metal-organic frameworks (MOFs) offers a pathway to overcome this limitation; however, most MOF-LIG hybrids have been applied to gas sensing, leaving liquid-phase analyte detection largely unexplored. To improve sensor's performance, MIL-100 MOF was incorporated onto the LIG electrodes via a simple drop-casting process. As a proof-of-concept, Ciprofloxacin detection was demonstrated with a detection limit of 6.04 nM. These findings establish MOF functionalized LIG electrodes as a versatile, low-cost, and scalable platform for sensitive solution-phase electrochemical sensing in environmental and biomedical applications.