ZnO/FTO based biosensor deposited via spin coating method for bacteria detection

Abstract

Transparent oxide conductors have been an up-and-coming research topic thanks to their excellent conductive and optoelectric properties. This type of materials are the basis for some of the current technological advances in areas such as sensing devices, transistors, and solar cells. A biosensor consists of an analog component that translates the presence of biomolecules or minerals into an electrical signal that can be processed and later interpreted by the user for future work. The adaptation of nanotechnology to biosensors can provide nanoscale analysis for the detection of biomolecules. The deposition of different nanomaterials into biosensors has made possible the creation of highly sensitive and selective biosensors, which are desired properties for sensing devices. This research presents the design of a ZnO/FTO-based amperometric biosensor deposited via spin coating technique for bacteria detection on a molecular scale. The deposition of a ZnO thin film layer provides detection capabilities to the FTO in order to determine the presence of bacteria. As the ZnO thin film layer serves as an active region, the presence of the bacteria induces a change in the current measured through the biosensor when a voltage is applied. The characterization of the ZnO thin film as well as the electrical characterization of the biosensor were performed in order to prove the functionality of the device. Material characterization revealed a successful deposition of ZnO in the FTO glass substrate, obtaining a compact thin film consisting of spherical agglomerations of material. The electrical characterization reveled a change in current to different bacteria samples employed at different concentrations with \textit{Escherichia coli} showcasing the most sensitive results. The obtained biosensors proved to be functional for the detection of the presence of bacteria in very controlled parameters, proving ZnO as an effective alternative for future nano-biosensor devices.