Laser-scribed graphene sensors on nail polish with tunable composition for electrochemical detection of nitrite and glucose

Laser-induced graphene (LIG) techniques enable the direct laser writing or scribing of conductive graphene electrodes on insulative polymer substrates without complicated synthesis or fabrication processes. The precursors of LIG essentially determine its quality and applications in various fields including electrochemical devices. Here, we demonstrate that the widely used nail polish (NP) is a promising precursor of LIG, which can be converted into 3D porous graphene electrodes in air using a 405 nm laser engraving machine. The produced nail polish-based LIG (NP-LIG) electrodes possess high conductivity, good mechanical property, and tunable composition and electrochemical activity. These unique properties make NP-LIG a promising platform for developing cost-effective electrochemical sensing devices. A robust flexible electrochemical sensor of nitrite was therefore constructed on NP-LIG using chitosan as a sensing material, which shows a sensitive and selective response for the detection of nitrite with a calibration range of 2.0–1000 μM and a detection limit of 0.9 μM (S/N = 3). In addition, a non-enzymatic glucose electrochemical sensor was constructed by doping NP-LIG with copper ions (Cu2+/NP-LIG), suggesting the doping ability of NP-LIG by a simple mixing method.