A disposable and flexible electrochemical sensor for the sensitive detection of heavy metals based on a one-step laser-induced surface modification: A new strategy for the batch fabrication of sensors

In this study, we developed a disposable and flexible electrochemical sensor for the sensitive determination of heavy metal ions based on an efficient one-step laser-induced surface modification. A flexible polyimide film was used as the substrate of the sensor, which was sprayed with a corresponding bismuth precursor ink to form a sensitive coating, i.e., bismuth nanoparticle@laser-induced graphene (BiNP@LIG). Then, Nafion was pipetted on BiNP@LIG to form a cover layer. The BiNP@LIG nanocomposite was successfully synthesized by laser irradiation (470 nm), and the composition of the obtained material was further verified by X-ray diffraction, energy dispersive spectroscopy and Raman spectroscopy. Moreover, the morphology of the BiNP@LIG nanocomposite was investigated by scanning electron microscopy, which showed that BiNPs were uniformly distributed on LIG, and the average diameter of the BiNPs was approximately 38 nm. Finally, a possible sensing mechanism of the Nafion/BiNP@LIG electrochemical sensor was proposed. The results show that the proposed electrochemical sensor exhibited satisfactory sensitivity and stability for the detection of Pb(II) and Cd(II). In addition, the laserinduced surface modification method proposed in this study could be an attractive candidate for the batch fabrication of sensors based on the noncontact, computer-controlled and pattern-making characteristics of laser induction.