This paper presents an integrated ZnO/multi-walled carbon nanotubes (MWCNTs) electrode in novel stacking paper-based microfluidic analytical device for electrochemical biosensor. The designed sensors were subjected to detect glucose and ascorbic acid in a simulated body fluid using electrochemical methods, including cyclic voltammetry and impedance spectroscopy. The composite of ZnO/multi-walled carbon nanotubes (MWCNTs) with variations in mass fractions of 0.1, 0.5, 1, 2, 4 and 8% MWCNTs for measuring ascorbic acid and glucose with concentrations spanning from 0.02 to 5.12mM. The best results are obtained by 2% of MWCNTs in composited electrode, in which linear characteristics (R2>0.8) of the current response value show a sensitivity (gradient) of 0.017 and 0.085 µA/mM.cm2 for ascorbic acid and glucose measurement, respectively. The electrochemical detection by means of impedance spectra shows a linearly decreasing trend of chemical capacitance with increasing concentration of glucose and ascorbic acid. However, in the present system it is not sufficient to specifically distinguish the frequency response associated to glucose and ascorbic acid.
Rapid Detection of Ascorbic Acid Based on a Dual-Electrode Sensor System Using a Powder Microelectrode Embedded with Carboxyl Multi-Walled Carbon Nanotubes