Final Report Summary - SOFST (Knowledge Transfer of Smart Optical Fibre Sensor Technology) There is a high demand for smart optical fibre sensor technologies due to increasing application needs in a wide range of sectors, including civil engineering, aerospace, maritime, energy and defence industries, as well as in medical, environmental and food sectors. Optical fibre sensors and applications have been rapidly developed over the last 20 years, but some vital technology challenges still remain, such as multiplexed sensor networks for large structures, multi-parameter function fibre sensors, optical fibre biosensors and fibre laser based sensors. The research objective of the SOFST is to explore novel micro/nano fibre sensor platforms by exploiting speciality fibres and functional coatings, together with advanced high resolution fibre laser sensing technologies for a wide range of industrial applications, especially for environment and food quality and security control. The project has provided a platform to integrate the Marie Curie fellow Dr Q Sun’s expertise and knowledge in optical fibre sensors, multiplexed sensor networks and fiber laser sensors with the Aston Institute of Photonic Technologies’ (AIPT) advanced fibre grating, nano/microfiber and new materials fabrication technology to develop novel smart optical fibre sensors and potential applications. In addition, this project is designed to transfer the knowledge from Dr Q Sun with strong background in optical fibre photonics, sensors and lasers and unique knowledge and skills in smart optical fibre sensor technologies to the EU host AIPT to establish a new research collaboration and provide training to the young Post-docs, Ph.D and Master students. Through this project, we have achieved a significant number of good results in smart optical fibre sensors, as listed below:(1) We firstly proposed a 3D encoded fiber microstructures based sensor network with hybrid TDM/WDM/FDM along a single fiber, resulting in ultra-high capacity up to 32000 sensing points in theory. A prototype fiber sensor network was performed assisted by a self-developed demodulation module with high response speed of 500Hz and high wavelength resolution less than 1pm.(2) We successfully inscribed FBGs on four core fiber and then investigated the thermal, strain and bending (both direction and magnitude) responses.(3) Intensive investigation on the few-mode microfiber based in-line MZI was conducted. We discovered the dispersion turning point of the few-mode microfiber to realize ultra-high positive and negative RI sensitivity for the first time to the best of our knowledge, which is of great significance to trace detection. (4) We proposed and demonstrated several dual-parameter sensors based on few-mode microfiber, including MZI structure, in-line mode interferometer, and reflective type sensing probe assisted by Fresnel reflection, which has the advantages of simple structure, compact size and multi-function.(5) We proposed and demonstrated a high sensitive temperature sensor and NH3 gas sensor based on a microfibre coated with graphene. Benefitting from the super-large specific surface area and fast electron transfer rate of graphene, the electrical properties and refractive index of graphene can be changed along with temperature or gas concentration, resulting the variation of transmission power, which provides low cost demodulation cost. (6) We performed a selective and high sensitive glucose sensor by immobilizing the Glucose oxidase (GOD) on a few-mode microfiber. Benefiting from the high RI sensitivity of few-mode microfiber, ultra-high sensitivity up to 4.47nm/(mg/ml) was realized within the dynamic range of 0-3.0mg/ml for selective glucose concentration sensor. (7) We produced an 81o-tilted fibre grating coated with single-walled carbon nanotubes to form a thin film overlay. Then, the surrounding RI change induced not only the resonant wavelength shift but also the power intensity change of the attenuation band in the transmission spectrum. (8) We produced an ultra-short DBR fibre laser constructed with strong FBG pair on EDF, and then embedded the laser cavity into textile. Deformation of the textile, involving the transverse force subjected by the laser cavity, is proportional to the change of the beat frequency of the laser. Laboratory studies demonstrate that the sensor could achieve real-time and accurate measurement of the weak and dynamical arterial pulse signal. (9) We designed and fabricated a cascaded microfibre knots with intrinsic Vernier effect, and further demonstrated super high resolution RI sensors up to 10-7RIU through spectrum magnification and fibre laser. (10) We participated the project on food quality control in close collaboration with Branscan, Arden Photonics and Warnurtons. A prototype of multi-point flour humidity and granularity sensor system was implemented by building a compact and distributed NIR detecting system associated with 45º TFGs.With Dr. Q Sun’s help, the research platform for optical fibre biosensors and laser sensors has been further improved at AIPT. Knowledge transfer from Dr. Q Sun to the host AIPT have been conducted by giving talks and seminars to the group and post-docs and Ph.D students. Dr. Sun has closely supervised three Ph.D students and one academic visiting student. She has given two talks on the results of her research work based on this project as follows:(i) “Micro/nano fibre based devices and their applications”, 7th floor, North Wing, Main building, Aston University, April 1, 2014.(ii) “Smart Optical Fibre Sensor Technologies”, 3th floor, North Wing, Main building Aston University, November 17, 2014.Furthermore, knowledge transfer to European co-hosts through some workshops and research collaborations. She participated the project on food quality control in close collaboration with Branscan, Arden Photonics and Warnurtons in UK. Besides, she has given a talk “Advanced optical fibre gratings and their sensing applications”, at City University London and initiated the joint work on smart fibre sensors based on large capacity sensor network. She also has established new research collaboration with ORC in University of Southampton on fabrication of nano/microfiber and optical fibre bio/chemical sensors.
