Smartphone-based electrochemical sensing of propyl gallate in food samples by employing NiFe-Oxide decorated flexible laser-induced graphene electrode

Flexible graphene electronics utilizing laser-induced graphene (LIG) technology offer an efficient, cost-effective, and mask-free approach to produce graphene in a single step. LIG can be directly patterned on polyimide films, impacting their surface properties, chemical composition, and electrical conductivity. However, the electrochemical performance of standalone LIG is limited. To address this, the study enhances LIG by synthesizing nickel-iron Prussian blue analogues through co-precipitation and calcination, forming porous NiFe-Oxide, which is subsequently deposited onto the LIG surface via a facile physical deposition method. The porous NiFe-Oxide@LIG electrode material demonstrates excellent electrochemical sensing capabilities due to its high conductivity, improved surface area, enhanced active sites, and superior electrocatalytic performance for detecting the antioxidant propyl gallate (PG). This porous NiFe-Oxide@LIG electrode material features a linear detection range (0.5–5 μM), low detection limit (0.01 μM), high sensitivity (17.12 μAμM⁻¹cm⁻²), and strong selectivity for PG. Additionally, it offers high reproducibility and repeatability, evidenced by the low relative standard deviation values of 2.61 % and 1.96 %, respectively. The practicality of the proposed sensor was validated using food samples, integrated into a smartphone-based sensing device, achieving satisfactory recovery rates above 79.2 %. This smartphone-based sensor enables effective onsite food quality and safety monitoring.