Integration of ZnO Nanorod Biosensor with Field-Effect Transistor

Recent technological advances in fabrication of novel hybridized semiconductors, and inorganic nanomaterials may provide the tools necessary to immobilize bio-molecules such as enzyme substrates. The objective of this research is to combine extended-gate field-effect transistors (EG-FET’s) with biosensing devices utilizing high aspect ratios of ZnO nanorods (NR’s) to achieve a high surface area for glucose immobilization. (EG-FET’s) provide a useful mechanism by aiding in sensitivity, and utilizing energy more efficiently. The method is carried out by means of electron-beam deposition; titanium is deposited on Si (001) substrate in a 20nm layer, followed by gold deposition of 100 nm. This is followed by a parametric, low temperature, hydrothermal microwave-irradiated growth of ZnO NR’s in (0001) orientation on the gold substrate. At this point the substrate undergoes a characterization process of optical microscopy, alpha-step profiling, x-ray diffraction, and scanning electron microscopy to ensure that proper growth has taken place. The substrate is then attached to a circuit board, with an (EG-FET) wired to the substrate via soldering. Glucose is then immobilized on the substrate using covalent and electrostatic bonding methods. Measurements can then be carried out using a semi-conductor parameter analyzer to measure the concentration and effect of glucose on current. Lastly, immobilized ZnO NR’s are characterized using x-ray photoelectron spectroscopy to observe that glucose was effectively immobilized. In conclusion the (EG-FET) effect on the biosensor will allow small changes in gate potential from immobilized enzyme substrates to alter the drain current output.