High levels of nitrates and nitrites harm human health and aquatic ecosystems, and their concentration varies dynamically, necessitating their simultaneous detection. Among electrodes for electrochemical sensors, Laser-induced graphene (LIG) offers a flexible, one-step alternative, yet CO2 laser interactions with Kapton remain underexplored. Optimization studies are not performed over entire range and defects on the surface are overlooked which are crucial for high electrochemical activity. This thesis develops LIG-based electrochemical sensors modified with nanomaterials for simultaneous...