Development Of Fabrication And Sensing Property Based On Optical Fiber-ZnO Hybrid Structure

Gas sensors have been widely applied in air quality monitoring,exhaust emissions testing and indoor-gas detection.With the development of science and technology,people put forward new requirements about the performance and application of gas sensors,aim to enhance the sensitivity,shorten the response/response time and improve the selectivity of the target gas.It shows the trend of miniaturization,flexibility and low power consumption about gas sensors with the application of nanotechnology.In this paper,we study on the design,the synthesis and the gas sensing test of the metal oxide micro-nanostructure,the structure and the function of the micro-heater,in order to develop micro gas sensors with high-integration and low-consumption.The main research work is described as follows:(a)A novel approach was developed for the enhanced growth of ZnO nanowires on optical fiber surface in this paper.The method combined a hydrothermal process with the internal UV irradiation from the fiber core,and the effect of UV irradiation on the growth behavior of ZnO nanowires was investigated.The results show that UV irradiation had great effect on the preferred growth orientation and the excellent quality of the ZnO nanowires.The crystallization velocity along the c-axis would increase rapidly with the increasing of the irradiation power,while the growth process in the lateral direction was marginally affected by the irradiation.The developed approach is applicable for the efficient growth of nanowires on the fiber surface.A mechanism was also proposed for the UV irradiation assisted growth process of ZnO nanowires to improve the design and the fabrication of the hybrid structure.(b)The gas sensor based on a novel ZnO nanowires/optical fiber hybrid structure was proposed in order to enhance the sensing properties of ethanol detection with UV irradiation.UV light would transmit through the optical fiber and ZnO nanowires would take part in the chemical reaction while the gas sensing test.The results showed that UV irradiation was able to enhance the sensitivity and shorten the response time,and the sensor performed a good long-term stability as well.The UV-assisted sensor could response to the low concentration at ppb-level of ethanol at relatively lower temperatures.(c)Design of a novel ZnO nanowires/Ti/optical fiber hybrid structure.Ti thin film is used as IR heater in gas sensing testing instead of heating circuit.The thermal radiation of the infrared light provides the temperature for the gas sensing response of ZnO nanowires.The validity of the IR heater is proved through the simulation and the gas sensing test to ethanol.The appropriate thickness of Ti thin film is 500 nm.The results of the response to ethanol show that the working temperature of ZnO nanowires in gas sensing test is 300 ? when the power of the IR light is 410 mW.