Abstract

Several studies have been conducted to find alternative methods to monitor blood glucose that might help to address a worldwide problem, diabetes. This current study focused on the fabrication of ZnO based non-enzymatic glucose biosensor. Zinc oxide (ZnO) films were synthesized via a modified Spray pyrolysis technique where Zinc chloride, ZnCl₂, was used as a precursor solution. The concentration of the precursor solution varied from 0.1M, 0.3M, and 0.5M. The substrate-to-nozzle distance of 5cm, substrate temperature of 300 ± 5°C, and deposition time of 30 minutes were held constant. Then, the ZnO films were deposited on a silicon wafer (1 0 0) and glass slide substrates with 1cm by 1cm dimension. The performance of both ZnO/Si and ZnO/glass electrodes were then evaluated in terms of their electrochemical activity towards glucose using a modified electrochemical setup using Gizduino, silver anode, and the fabricated ZnO/Si or ZnO/glass as the cathode in phosphate buffer solution. In both XRD and Raman Spectroscopy characterization, it was confirmed that the synthesized materials on both substrates were ZnO of hexagonal wurtzite type. The growth of ZnO on the samples takes place due to a fast chemical reaction once the atomized solution reached the substrate. ZnCl₂ in the precursor solution is dissociated into ZnO_(s), HCl_(aq), and H₂O_(l) upon application of heat. Since the precursor concentration was varied and the deposition time was held constant at 30 minutes then the result is expected that there is a higher yield on the samples synthesized with higher precursor concentrations. For both 0.5M ZnO/Si and 0.5M ZnO/glass samples, faster response time was observed for higher glucose concentration because the samples easily detect the presence of glucose in the system for higher concentration leads to faster oxidation and is a direct implication of the free path of electrons from the surface of the deposited ZnO films as it is known that ZnO has novel electron transport properties. From the electrochemical analyses, the fabricated electrodes (ZnO/Si and ZnO/glass) have the potential for glucose biosensing. It was also found that for higher glucose concentration, 0.5M samples of both ZnO/Si and ZnO/glass have a faster response time. Moreover, all different molarity varied (0.1M, 0.3M, and 0.5M) samples of both ZnO/Si and ZnO/glass exhibited good electrochemical response toward glucose with the current response that ranges from approximately 1mA to 9mA. Furthermore, this study has shown that a low-cost glucose sensor can be fabricatedusing spray pyrolysis.

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