Integrating Sensors With Nanostructures for Biomedical Applications

This paper presents the fabrication of sensors that are integrated with nanostructures and bio-functionalized to create novel devices for biomedical applications. Biosensors are in great demand for various applications including for the agriculture and food industries, environmental monitoring, and medical diagnostics. Much research is being focused on the use of nanostructures (nanowires, nanotubes, nanoparticles, etc.) to provide for miniaturization and improved performance of these devices. The use of nanostructures is favorable for such applications since their sizes are closer to that of biological and chemical species and therefore, improve the signal generated. Moreover, their high surface-to-volume ratio results in devices with very high sensitivity. The use of nanotechnology leads to smaller, lower-power smart devices. Thus, this paper presents the integration of sensors with nanostructures for biomedical applications, specifically, glucose sensing. In the work presented, a glucose biosensor and its fabrication process flow are described. The device is based on electrochemical sensing using a working electrode with bio-functionalized zinc oxide (ZnO) nano-rods. Among all metal oxide nanostructures, ZnO nano-materials play a significant role as a sensing element in biosensors due to their properties such as high isoelectric point (IEP), fast electron transfer, non-toxicity, biocompatibility, and chemical stability which are very crucial parameters to achieve high sensitivity. Amperometric enzyme electrodes based on glucose oxidase (GOx) are used due to their stability and high selectivity to glucose. The device also consists of silicon dioxide and titanium layers as well as platinum working and counter electrodes and a silver/silver chloride reference electrode. The chlorination process on the reference electrode was optimized for various times using field emission scanning electron microscope (FESEM) and energy-dispersive X-ray spectroscopy (EDS or EDX) measurements. The ZnO nanorods were grown using the hydrothermal method and will be bio-functionalized with GOx for electrochemical sensing. Once completed, the sensors will be tested to characterize their performance, including their sensitivity and stability.