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This study proposed a nonenzymatic sensor for lactic acid detection based on copper doped zinc oxide (CZO) modified by graphitic carbon nitride (g-C3N4) and iron–platinum nanoparticles (FePt NPs). The silver paste electrodes of the sensor were prepared using screen printing technology, and the CZO sensing film was deposited using radio frequency (R.F.) sputtering system. The g-C3N4 nanosheet solution was prepared through liquid exfoliating of the g-C3N4 in water. The sensing film was modified by adding different contents of the FePt NPs in g-C3N4 solution. The various concentrations of the FePt NPs were 0.03, 0.1, and 0.3 wt%. The ${V}$ – ${T}$ measurement system was applied to investigate the sensing characteristics of the lactic acid sensors based on CZO sensing film modified by g-C3N4 and FePt NPs. The surface morphology of the sensor was analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS). In this work, the 0.1 wt% FePt NPs-g-C3N4 lactic acid sensor has the best sensitivity, linearity, response time, and the limit of detection (LOD). [ABSTRACT FROM AUTHOR]

Potentiometric biosensors based on flexible arrayed silver paste electrode and copper-doped zinc oxide sensing film modified by iron-platinum nanoparticles (FePt NPs) are designed and manufactured to detect lactate in human. The sensing film is made of copper-doped zinc oxide (CZO) by a radio frequency (RF) sputtering system, and then modified by iron-platinum nanoparticles (FePt NPs). The surface morphology of copper-doped zinc oxide (CZO) is analyzed by scanning electron microscope (SEM). FePt NPs are analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The average sensitivity, response time, and interference effect of the lactate biosensors are analyzed by voltage-time (V-T) measurement system. The electrochemical impedance is analyzed by electrochemical impedance spectroscopy (EIS). The average sensitivity and linearity over the concentration range 0.2–5 mM are 25.32 mV/mM and 0.977 mV/mM, respectively. The response time of the lactate biosensor is 16 s, with excellent selectivity. [ABSTRACT FROM AUTHOR]